// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta */
#include <stddef.h>
#include <string.h>
#include <stdbool.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/pkt_cls.h>
#include <sys/socket.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include "test_iptunnel_common.h"
#include "bpf_kfuncs.h"
#define tcphdr_sz sizeof(struct tcphdr)
#define udphdr_sz sizeof(struct udphdr)
#define ethhdr_sz sizeof(struct ethhdr)
#define iphdr_sz sizeof(struct iphdr)
#define ipv6hdr_sz sizeof(struct ipv6hdr)
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(max_entries, 256);
__type(key, __u32);
__type(value, __u64);
} rxcnt SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_IPTNL_ENTRIES);
__type(key, struct vip);
__type(value, struct iptnl_info);
} vip2tnl SEC(".maps");
static __always_inline void count_tx(__u32 protocol)
{
__u64 *rxcnt_count;
rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
if (rxcnt_count)
*rxcnt_count += 1;
}
static __always_inline int get_dport(void *trans_data, __u8 protocol)
{
struct tcphdr *th;
struct udphdr *uh;
switch (protocol) {
case IPPROTO_TCP:
th = (struct tcphdr *)trans_data;
return th->dest;
case IPPROTO_UDP:
uh = (struct udphdr *)trans_data;
return uh->dest;
default:
return 0;
}
}
static __always_inline void set_ethhdr(struct ethhdr *new_eth,
const struct ethhdr *old_eth,
const struct iptnl_info *tnl,
__be16 h_proto)
{
memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
new_eth->h_proto = h_proto;
}
static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
{
__u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz];
__u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz];
__u8 iph_buffer_udp[iphdr_sz + udphdr_sz];
struct bpf_dynptr new_xdp_ptr;
struct iptnl_info *tnl;
struct ethhdr *new_eth;
struct ethhdr *old_eth;
struct iphdr *iph;
__u16 *next_iph;
__u16 payload_len;
struct vip vip = {};
int dport;
__u32 csum = 0;
int i;
__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
__builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp));
__builtin_memset(iph_buffer_udp, 0, sizeof(iph_buffer_udp));
if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_udp, sizeof(iph_buffer_udp));
else
iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_tcp, sizeof(iph_buffer_tcp));
if (!iph)
return XDP_DROP;
dport = get_dport(iph + 1, iph->protocol);
if (dport == -1)
return XDP_DROP;
vip.protocol = iph->protocol;
vip.family = AF_INET;
vip.daddr.v4 = iph->daddr;
vip.dport = dport;
payload_len = bpf_ntohs(iph->tot_len);
tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
/* It only does v4-in-v4 */
if (!tnl || tnl->family != AF_INET)
return XDP_PASS;
if (bpf_xdp_adjust_head(xdp, 0 - (int)iphdr_sz))
return XDP_DROP;
bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
if (!new_eth)
return XDP_DROP;
iph = (struct iphdr *)(new_eth + 1);
old_eth = (struct ethhdr *)(iph + 1);
set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
if (new_eth == eth_buffer)
bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
iph->version = 4;
iph->ihl = iphdr_sz >> 2;
iph->frag_off = 0;
iph->protocol = IPPROTO_IPIP;
iph->check = 0;
iph->tos = 0;
iph->tot_len = bpf_htons(payload_len + iphdr_sz);
iph->daddr = tnl->daddr.v4;
iph->saddr = tnl->saddr.v4;
iph->ttl = 8;
next_iph = (__u16 *)iph;
for (i = 0; i < iphdr_sz >> 1; i++)
csum += *next_iph++;
iph->check = ~((csum & 0xffff) + (csum >> 16));
count_tx(vip.protocol);
return XDP_TX;
}
static __always_inline int handle_ipv6(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
{
__u8 eth_buffer[ethhdr_sz + ipv6hdr_sz + ethhdr_sz];
__u8 ip6h_buffer_tcp[ipv6hdr_sz + tcphdr_sz];
__u8 ip6h_buffer_udp[ipv6hdr_sz + udphdr_sz];
struct bpf_dynptr new_xdp_ptr;
struct iptnl_info *tnl;
struct ethhdr *new_eth;
struct ethhdr *old_eth;
struct ipv6hdr *ip6h;
__u16 payload_len;
struct vip vip = {};
int dport;
__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
__builtin_memset(ip6h_buffer_tcp, 0, sizeof(ip6h_buffer_tcp));
__builtin_memset(ip6h_buffer_udp, 0, sizeof(ip6h_buffer_udp));
if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_udp, sizeof(ip6h_buffer_udp));
else
ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_tcp, sizeof(ip6h_buffer_tcp));
if (!ip6h)
return XDP_DROP;
dport = get_dport(ip6h + 1, ip6h->nexthdr);
if (dport == -1)
return XDP_DROP;
vip.protocol = ip6h->nexthdr;
vip.family = AF_INET6;
memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
vip.dport = dport;
payload_len = ip6h->payload_len;
tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
/* It only does v6-in-v6 */
if (!tnl || tnl->family != AF_INET6)
return XDP_PASS;
if (bpf_xdp_adjust_head(xdp, 0 - (int)ipv6hdr_sz))
return XDP_DROP;
bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
if (!new_eth)
return XDP_DROP;
ip6h = (struct ipv6hdr *)(new_eth + 1);
old_eth = (struct ethhdr *)(ip6h + 1);
set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
if (new_eth == eth_buffer)
bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
ip6h->version = 6;
ip6h->priority = 0;
memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + ipv6hdr_sz);
ip6h->nexthdr = IPPROTO_IPV6;
ip6h->hop_limit = 8;
memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
count_tx(vip.protocol);
return XDP_TX;
}
SEC("xdp")
int _xdp_tx_iptunnel(struct xdp_md *xdp)
{
__u8 buffer[ethhdr_sz];
struct bpf_dynptr ptr;
struct ethhdr *eth;
__u16 h_proto;
__builtin_memset(buffer, 0, sizeof(buffer));
bpf_dynptr_from_xdp(xdp, 0, &ptr);
eth = bpf_dynptr_slice(&ptr, 0, buffer, sizeof(buffer));
if (!eth)
return XDP_DROP;
h_proto = eth->h_proto;
if (h_proto == bpf_htons(ETH_P_IP))
return handle_ipv4(xdp, &ptr);
else if (h_proto == bpf_htons(ETH_P_IPV6))
return handle_ipv6(xdp, &ptr);
else
return XDP_DROP;
}
char _license[] SEC("license") = "GPL";
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