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![Lorenzo Bianconi](/assets/img/avatar_default.png)
Rely on the libbpf skeleton facility and other utilities provided by XDP sample helpers in xdp_router_ipv4 sample. Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/7f4d98ee2c13c04d5eb924eebf79ced32fee8418.1647414711.git.lorenzo@kernel.org
180 lines
3.8 KiB
C
180 lines
3.8 KiB
C
/* Copyright (C) 2017 Cavium, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2 of the GNU General Public License
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* as published by the Free Software Foundation.
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*/
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#include "vmlinux.h"
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#include "xdp_sample.bpf.h"
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#include "xdp_sample_shared.h"
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#define ETH_ALEN 6
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#define ETH_P_8021Q 0x8100
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#define ETH_P_8021AD 0x88A8
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struct trie_value {
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__u8 prefix[4];
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__be64 value;
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int ifindex;
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int metric;
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__be32 gw;
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};
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/* Key for lpm_trie */
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union key_4 {
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u32 b32[2];
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u8 b8[8];
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};
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struct arp_entry {
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__be64 mac;
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__be32 dst;
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};
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struct direct_map {
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struct arp_entry arp;
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int ifindex;
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__be64 mac;
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};
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/* Map for trie implementation */
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struct {
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__uint(type, BPF_MAP_TYPE_LPM_TRIE);
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__uint(key_size, 8);
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__uint(value_size, sizeof(struct trie_value));
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__uint(max_entries, 50);
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__uint(map_flags, BPF_F_NO_PREALLOC);
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} lpm_map SEC(".maps");
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/* Map for ARP table */
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__type(key, __be32);
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__type(value, __be64);
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__uint(max_entries, 50);
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} arp_table SEC(".maps");
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/* Map to keep the exact match entries in the route table */
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__type(key, __be32);
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__type(value, struct direct_map);
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__uint(max_entries, 50);
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} exact_match SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_DEVMAP);
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__uint(key_size, sizeof(int));
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__uint(value_size, sizeof(int));
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__uint(max_entries, 100);
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} tx_port SEC(".maps");
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SEC("xdp")
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int xdp_router_ipv4_prog(struct xdp_md *ctx)
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{
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void *data_end = (void *)(long)ctx->data_end;
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void *data = (void *)(long)ctx->data;
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struct ethhdr *eth = data;
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u64 nh_off = sizeof(*eth);
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struct datarec *rec;
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__be16 h_proto;
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u32 key = 0;
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rec = bpf_map_lookup_elem(&rx_cnt, &key);
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if (rec)
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NO_TEAR_INC(rec->processed);
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if (data + nh_off > data_end)
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goto drop;
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h_proto = eth->h_proto;
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if (h_proto == bpf_htons(ETH_P_8021Q) ||
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h_proto == bpf_htons(ETH_P_8021AD)) {
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struct vlan_hdr *vhdr;
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vhdr = data + nh_off;
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nh_off += sizeof(struct vlan_hdr);
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if (data + nh_off > data_end)
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goto drop;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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switch (bpf_ntohs(h_proto)) {
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case ETH_P_ARP:
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if (rec)
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NO_TEAR_INC(rec->xdp_pass);
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return XDP_PASS;
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case ETH_P_IP: {
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struct iphdr *iph = data + nh_off;
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struct direct_map *direct_entry;
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__be64 *dest_mac, *src_mac;
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int forward_to;
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if (iph + 1 > data_end)
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goto drop;
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direct_entry = bpf_map_lookup_elem(&exact_match, &iph->daddr);
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/* Check for exact match, this would give a faster lookup */
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if (direct_entry && direct_entry->mac &&
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direct_entry->arp.mac) {
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src_mac = &direct_entry->mac;
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dest_mac = &direct_entry->arp.mac;
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forward_to = direct_entry->ifindex;
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} else {
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struct trie_value *prefix_value;
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union key_4 key4;
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/* Look up in the trie for lpm */
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key4.b32[0] = 32;
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key4.b8[4] = iph->daddr & 0xff;
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key4.b8[5] = (iph->daddr >> 8) & 0xff;
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key4.b8[6] = (iph->daddr >> 16) & 0xff;
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key4.b8[7] = (iph->daddr >> 24) & 0xff;
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prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
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if (!prefix_value)
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goto drop;
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forward_to = prefix_value->ifindex;
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src_mac = &prefix_value->value;
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if (!src_mac)
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goto drop;
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dest_mac = bpf_map_lookup_elem(&arp_table, &iph->daddr);
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if (!dest_mac) {
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if (!prefix_value->gw)
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goto drop;
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dest_mac = bpf_map_lookup_elem(&arp_table,
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&prefix_value->gw);
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}
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}
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if (src_mac && dest_mac) {
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int ret;
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__builtin_memcpy(eth->h_dest, dest_mac, ETH_ALEN);
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__builtin_memcpy(eth->h_source, src_mac, ETH_ALEN);
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ret = bpf_redirect_map(&tx_port, forward_to, 0);
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if (ret == XDP_REDIRECT) {
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if (rec)
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NO_TEAR_INC(rec->xdp_redirect);
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return ret;
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}
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}
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}
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default:
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break;
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}
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drop:
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if (rec)
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NO_TEAR_INC(rec->xdp_drop);
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return XDP_DROP;
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}
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char _license[] SEC("license") = "GPL";
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