257 lines
6.6 KiB
C
257 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Meta */
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#include <stddef.h>
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#include <string.h>
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#include <stdbool.h>
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#include <linux/bpf.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/ip.h>
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#include <linux/ipv6.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/tcp.h>
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#include <linux/pkt_cls.h>
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#include <sys/socket.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_endian.h>
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#include "test_iptunnel_common.h"
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#include "bpf_kfuncs.h"
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const size_t tcphdr_sz = sizeof(struct tcphdr);
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const size_t udphdr_sz = sizeof(struct udphdr);
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const size_t ethhdr_sz = sizeof(struct ethhdr);
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const size_t iphdr_sz = sizeof(struct iphdr);
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const size_t ipv6hdr_sz = sizeof(struct ipv6hdr);
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(max_entries, 256);
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__type(key, __u32);
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__type(value, __u64);
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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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__uint(max_entries, MAX_IPTNL_ENTRIES);
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__type(key, struct vip);
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__type(value, struct iptnl_info);
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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, __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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return th->dest;
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case IPPROTO_UDP:
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uh = (struct udphdr *)trans_data;
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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, struct bpf_dynptr *xdp_ptr)
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{
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__u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz];
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__u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz];
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__u8 iph_buffer_udp[iphdr_sz + udphdr_sz];
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struct bpf_dynptr new_xdp_ptr;
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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;
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__u16 *next_iph;
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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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__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
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__builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp));
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__builtin_memset(iph_buffer_udp, 0, sizeof(iph_buffer_udp));
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if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
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iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_udp, sizeof(iph_buffer_udp));
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else
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iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_tcp, sizeof(iph_buffer_tcp));
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if (!iph)
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return XDP_DROP;
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dport = get_dport(iph + 1, 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 = bpf_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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if (bpf_xdp_adjust_head(xdp, 0 - (int)iphdr_sz))
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return XDP_DROP;
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bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
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new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
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if (!new_eth)
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return XDP_DROP;
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iph = (struct iphdr *)(new_eth + 1);
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old_eth = (struct ethhdr *)(iph + 1);
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set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
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if (new_eth == eth_buffer)
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bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
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iph->version = 4;
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iph->ihl = iphdr_sz >> 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 = bpf_htons(payload_len + iphdr_sz);
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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 *)iph;
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for (i = 0; i < iphdr_sz >> 1; i++)
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csum += *next_iph++;
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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, struct bpf_dynptr *xdp_ptr)
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{
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__u8 eth_buffer[ethhdr_sz + ipv6hdr_sz + ethhdr_sz];
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__u8 ip6h_buffer_tcp[ipv6hdr_sz + tcphdr_sz];
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__u8 ip6h_buffer_udp[ipv6hdr_sz + udphdr_sz];
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struct bpf_dynptr new_xdp_ptr;
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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;
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__u16 payload_len;
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struct vip vip = {};
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int dport;
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__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
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__builtin_memset(ip6h_buffer_tcp, 0, sizeof(ip6h_buffer_tcp));
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__builtin_memset(ip6h_buffer_udp, 0, sizeof(ip6h_buffer_udp));
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if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
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ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_udp, sizeof(ip6h_buffer_udp));
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else
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ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_tcp, sizeof(ip6h_buffer_tcp));
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if (!ip6h)
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return XDP_DROP;
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dport = get_dport(ip6h + 1, 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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if (bpf_xdp_adjust_head(xdp, 0 - (int)ipv6hdr_sz))
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return XDP_DROP;
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bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
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new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
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if (!new_eth)
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return XDP_DROP;
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ip6h = (struct ipv6hdr *)(new_eth + 1);
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old_eth = (struct ethhdr *)(ip6h + 1);
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set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
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if (new_eth == eth_buffer)
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bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
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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 = bpf_htons(bpf_ntohs(payload_len) + ipv6hdr_sz);
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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")
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int _xdp_tx_iptunnel(struct xdp_md *xdp)
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{
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__u8 buffer[ethhdr_sz];
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struct bpf_dynptr ptr;
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struct ethhdr *eth;
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__u16 h_proto;
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__builtin_memset(buffer, 0, sizeof(buffer));
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bpf_dynptr_from_xdp(xdp, 0, &ptr);
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eth = bpf_dynptr_slice(&ptr, 0, buffer, sizeof(buffer));
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if (!eth)
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return XDP_DROP;
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h_proto = eth->h_proto;
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if (h_proto == bpf_htons(ETH_P_IP))
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return handle_ipv4(xdp, &ptr);
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else if (h_proto == bpf_htons(ETH_P_IPV6))
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return handle_ipv6(xdp, &ptr);
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else
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return XDP_DROP;
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}
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char _license[] SEC("license") = "GPL";
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