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![Andy Gospodarek](/assets/img/avatar_default.png)
This changes the section name for the bpf program embedded in these files to "xdp.frags" to allow the programs to be loaded on drivers that are using an MTU greater than PAGE_SIZE. Rather than directly accessing the buffers, the packet data is now accessed via xdp helper functions to provide an example for those who may need to write more complex programs. v2: remove new unnecessary variable Signed-off-by: Andy Gospodarek <gospo@broadcom.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Lorenzo Bianconi <lorenzo@kernel.org> Link: https://lore.kernel.org/r/20220621175402.35327-1-gospo@broadcom.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
237 lines
5.6 KiB
C
237 lines
5.6 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program shows how to use bpf_xdp_adjust_head() by
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* encapsulating the incoming packet in an IPv4/v6 header
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* and then XDP_TX it out.
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*/
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#define KBUILD_MODNAME "foo"
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#include <uapi/linux/bpf.h>
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#include <linux/in.h>
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#include <linux/if_ether.h>
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#include <linux/if_packet.h>
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#include <linux/if_vlan.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <bpf/bpf_helpers.h>
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#include "xdp_tx_iptunnel_common.h"
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__type(key, __u32);
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__type(value, __u64);
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__uint(max_entries, 256);
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} rxcnt SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__type(key, struct vip);
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__type(value, struct iptnl_info);
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__uint(max_entries, MAX_IPTNL_ENTRIES);
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} vip2tnl SEC(".maps");
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static __always_inline void count_tx(u32 protocol)
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{
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u64 *rxcnt_count;
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rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
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if (rxcnt_count)
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*rxcnt_count += 1;
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}
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static __always_inline int get_dport(void *trans_data, void *data_end,
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u8 protocol)
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{
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struct tcphdr *th;
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struct udphdr *uh;
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switch (protocol) {
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case IPPROTO_TCP:
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th = (struct tcphdr *)trans_data;
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if (th + 1 > data_end)
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return -1;
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return th->dest;
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case IPPROTO_UDP:
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uh = (struct udphdr *)trans_data;
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if (uh + 1 > data_end)
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return -1;
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return uh->dest;
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default:
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return 0;
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}
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}
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static __always_inline void set_ethhdr(struct ethhdr *new_eth,
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const struct ethhdr *old_eth,
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const struct iptnl_info *tnl,
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__be16 h_proto)
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{
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memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
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memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
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new_eth->h_proto = h_proto;
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}
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static __always_inline int handle_ipv4(struct xdp_md *xdp)
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{
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void *data_end = (void *)(long)xdp->data_end;
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void *data = (void *)(long)xdp->data;
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struct iptnl_info *tnl;
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struct ethhdr *new_eth;
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struct ethhdr *old_eth;
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struct iphdr *iph = data + sizeof(struct ethhdr);
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u16 *next_iph_u16;
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u16 payload_len;
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struct vip vip = {};
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int dport;
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u32 csum = 0;
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int i;
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if (iph + 1 > data_end)
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return XDP_DROP;
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dport = get_dport(iph + 1, data_end, iph->protocol);
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if (dport == -1)
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return XDP_DROP;
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vip.protocol = iph->protocol;
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vip.family = AF_INET;
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vip.daddr.v4 = iph->daddr;
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vip.dport = dport;
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payload_len = ntohs(iph->tot_len);
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tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
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/* It only does v4-in-v4 */
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if (!tnl || tnl->family != AF_INET)
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return XDP_PASS;
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/* The vip key is found. Add an IP header and send it out */
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if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
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return XDP_DROP;
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data = (void *)(long)xdp->data;
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data_end = (void *)(long)xdp->data_end;
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new_eth = data;
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iph = data + sizeof(*new_eth);
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old_eth = data + sizeof(*iph);
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if (new_eth + 1 > data_end ||
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old_eth + 1 > data_end ||
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iph + 1 > data_end)
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return XDP_DROP;
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set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IP));
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iph->version = 4;
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iph->ihl = sizeof(*iph) >> 2;
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iph->frag_off = 0;
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iph->protocol = IPPROTO_IPIP;
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iph->check = 0;
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iph->tos = 0;
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iph->tot_len = htons(payload_len + sizeof(*iph));
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iph->daddr = tnl->daddr.v4;
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iph->saddr = tnl->saddr.v4;
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iph->ttl = 8;
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next_iph_u16 = (u16 *)iph;
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#pragma clang loop unroll(full)
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for (i = 0; i < sizeof(*iph) >> 1; i++)
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csum += *next_iph_u16++;
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iph->check = ~((csum & 0xffff) + (csum >> 16));
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count_tx(vip.protocol);
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return XDP_TX;
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}
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static __always_inline int handle_ipv6(struct xdp_md *xdp)
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{
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void *data_end = (void *)(long)xdp->data_end;
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void *data = (void *)(long)xdp->data;
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struct iptnl_info *tnl;
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struct ethhdr *new_eth;
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struct ethhdr *old_eth;
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struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
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__u16 payload_len;
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struct vip vip = {};
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int dport;
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if (ip6h + 1 > data_end)
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return XDP_DROP;
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dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
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if (dport == -1)
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return XDP_DROP;
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vip.protocol = ip6h->nexthdr;
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vip.family = AF_INET6;
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memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
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vip.dport = dport;
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payload_len = ip6h->payload_len;
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tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
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/* It only does v6-in-v6 */
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if (!tnl || tnl->family != AF_INET6)
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return XDP_PASS;
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/* The vip key is found. Add an IP header and send it out */
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if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
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return XDP_DROP;
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data = (void *)(long)xdp->data;
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data_end = (void *)(long)xdp->data_end;
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new_eth = data;
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ip6h = data + sizeof(*new_eth);
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old_eth = data + sizeof(*ip6h);
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if (new_eth + 1 > data_end ||
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old_eth + 1 > data_end ||
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ip6h + 1 > data_end)
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return XDP_DROP;
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set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IPV6));
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ip6h->version = 6;
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ip6h->priority = 0;
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memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
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ip6h->payload_len = htons(ntohs(payload_len) + sizeof(*ip6h));
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ip6h->nexthdr = IPPROTO_IPV6;
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ip6h->hop_limit = 8;
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memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
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memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
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count_tx(vip.protocol);
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return XDP_TX;
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}
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SEC("xdp.frags")
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int _xdp_tx_iptunnel(struct xdp_md *xdp)
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{
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void *data_end = (void *)(long)xdp->data_end;
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void *data = (void *)(long)xdp->data;
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struct ethhdr *eth = data;
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__u16 h_proto;
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if (eth + 1 > data_end)
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return XDP_DROP;
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h_proto = eth->h_proto;
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if (h_proto == htons(ETH_P_IP))
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return handle_ipv4(xdp);
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else if (h_proto == htons(ETH_P_IPV6))
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return handle_ipv6(xdp);
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else
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";
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