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3e29cd0e65
Implements port to port forwarding with route table and arp table lookup for ipv4 packets using bpf_redirect helper function and lpm_trie map. Signed-off-by: Christina Jacob <Christina.Jacob@cavium.com> Signed-off-by: David S. Miller <davem@davemloft.net>
187 lines
4.4 KiB
C
187 lines
4.4 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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#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_helpers.h"
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#include <linux/slab.h>
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#include <net/ip_fib.h>
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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 bpf_map_def SEC("maps") lpm_map = {
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.type = BPF_MAP_TYPE_LPM_TRIE,
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.key_size = 8,
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.value_size = sizeof(struct trie_value),
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.max_entries = 50,
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.map_flags = BPF_F_NO_PREALLOC,
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};
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/* Map for counter*/
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struct bpf_map_def SEC("maps") rxcnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u64),
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.max_entries = 256,
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};
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/* Map for ARP table*/
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struct bpf_map_def SEC("maps") arp_table = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(__be32),
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.value_size = sizeof(__be64),
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.max_entries = 50,
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};
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/* Map to keep the exact match entries in the route table*/
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struct bpf_map_def SEC("maps") exact_match = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(__be32),
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.value_size = sizeof(struct direct_map),
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.max_entries = 50,
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};
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struct bpf_map_def SEC("maps") tx_port = {
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.type = BPF_MAP_TYPE_DEVMAP,
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.key_size = sizeof(int),
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.value_size = sizeof(int),
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.max_entries = 100,
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};
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/* Function to set source and destination mac of the packet */
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static inline void set_src_dst_mac(void *data, void *src, void *dst)
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{
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unsigned short *source = src;
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unsigned short *dest = dst;
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unsigned short *p = data;
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__builtin_memcpy(p, dest, 6);
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__builtin_memcpy(p + 3, source, 6);
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}
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/* Parse IPV4 packet to get SRC, DST IP and protocol */
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static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
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__be32 *src, __be32 *dest)
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{
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struct iphdr *iph = data + nh_off;
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if (iph + 1 > data_end)
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return 0;
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*src = iph->saddr;
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*dest = iph->daddr;
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return iph->protocol;
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}
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SEC("xdp_router_ipv4")
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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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__be64 *dest_mac = NULL, *src_mac = NULL;
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void *data = (void *)(long)ctx->data;
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struct trie_value *prefix_value;
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int rc = XDP_DROP, forward_to;
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struct ethhdr *eth = data;
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union key_4 key4;
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long *value;
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u16 h_proto;
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u32 ipproto;
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u64 nh_off;
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nh_off = sizeof(*eth);
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if (data + nh_off > data_end)
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return rc;
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h_proto = eth->h_proto;
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if (h_proto == htons(ETH_P_8021Q) || h_proto == 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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return rc;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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if (h_proto == htons(ETH_P_ARP)) {
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return XDP_PASS;
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} else if (h_proto == htons(ETH_P_IP)) {
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struct direct_map *direct_entry;
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__be32 src_ip = 0, dest_ip = 0;
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ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
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direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
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/* Check for exact match, this would give a faster lookup*/
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if (direct_entry && direct_entry->mac && 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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/* Look up in the trie for lpm*/
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key4.b32[0] = 32;
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key4.b8[4] = dest_ip & 0xff;
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key4.b8[5] = (dest_ip >> 8) & 0xff;
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key4.b8[6] = (dest_ip >> 16) & 0xff;
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key4.b8[7] = (dest_ip >> 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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return XDP_DROP;
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src_mac = &prefix_value->value;
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if (!src_mac)
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return XDP_DROP;
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dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
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if (!dest_mac) {
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if (!prefix_value->gw)
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return XDP_DROP;
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dest_ip = prefix_value->gw;
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dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
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}
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forward_to = prefix_value->ifindex;
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}
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} else {
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ipproto = 0;
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}
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if (src_mac && dest_mac) {
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set_src_dst_mac(data, src_mac, dest_mac);
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value = bpf_map_lookup_elem(&rxcnt, &ipproto);
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if (value)
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*value += 1;
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return bpf_redirect_map(&tx_port, forward_to, 0);
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}
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return rc;
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}
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char _license[] SEC("license") = "GPL";
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