| // SPDX-License-Identifier: GPL-2.0 |
| #include <vmlinux.h> |
| #include <bpf/bpf_helpers.h> |
| |
| #define ETH_ALEN 6 |
| #define HDR_SZ (sizeof(struct ethhdr) + sizeof(struct ipv6hdr) + sizeof(struct udphdr)) |
| const volatile int ifindex_out; |
| const volatile int ifindex_in; |
| const volatile __u8 expect_dst[ETH_ALEN]; |
| volatile int pkts_seen_xdp = 0; |
| volatile int pkts_seen_zero = 0; |
| volatile int pkts_seen_tc = 0; |
| volatile int retcode = XDP_REDIRECT; |
| |
| SEC("xdp") |
| int xdp_redirect(struct xdp_md *xdp) |
| { |
| __u32 *metadata = (void *)(long)xdp->data_meta; |
| void *data_end = (void *)(long)xdp->data_end; |
| void *data = (void *)(long)xdp->data; |
| |
| __u8 *payload = data + HDR_SZ; |
| int ret = retcode; |
| |
| if (payload + 1 > data_end) |
| return XDP_ABORTED; |
| |
| if (xdp->ingress_ifindex != ifindex_in) |
| return XDP_ABORTED; |
| |
| if (metadata + 1 > data) |
| return XDP_ABORTED; |
| |
| if (*metadata != 0x42) |
| return XDP_ABORTED; |
| |
| if (*payload == 0) { |
| *payload = 0x42; |
| pkts_seen_zero++; |
| } |
| |
| if (bpf_xdp_adjust_meta(xdp, 4)) |
| return XDP_ABORTED; |
| |
| if (retcode > XDP_PASS) |
| retcode--; |
| |
| if (ret == XDP_REDIRECT) |
| return bpf_redirect(ifindex_out, 0); |
| |
| return ret; |
| } |
| |
| static bool check_pkt(void *data, void *data_end) |
| { |
| struct ipv6hdr *iph = data + sizeof(struct ethhdr); |
| __u8 *payload = data + HDR_SZ; |
| |
| if (payload + 1 > data_end) |
| return false; |
| |
| if (iph->nexthdr != IPPROTO_UDP || *payload != 0x42) |
| return false; |
| |
| /* reset the payload so the same packet doesn't get counted twice when |
| * it cycles back through the kernel path and out the dst veth |
| */ |
| *payload = 0; |
| return true; |
| } |
| |
| SEC("xdp") |
| int xdp_count_pkts(struct xdp_md *xdp) |
| { |
| void *data = (void *)(long)xdp->data; |
| void *data_end = (void *)(long)xdp->data_end; |
| |
| if (check_pkt(data, data_end)) |
| pkts_seen_xdp++; |
| |
| /* Return XDP_DROP to make sure the data page is recycled, like when it |
| * exits a physical NIC. Recycled pages will be counted in the |
| * pkts_seen_zero counter above. |
| */ |
| return XDP_DROP; |
| } |
| |
| SEC("tc") |
| int tc_count_pkts(struct __sk_buff *skb) |
| { |
| void *data = (void *)(long)skb->data; |
| void *data_end = (void *)(long)skb->data_end; |
| |
| if (check_pkt(data, data_end)) |
| pkts_seen_tc++; |
| |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |