| // 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)) |
| |
| /** |
| * enum frame_mark - magics to distinguish page/packet paths |
| * @MARK_XMIT: page was recycled due to the frame being "xmitted" by the NIC. |
| * @MARK_IN: frame is being processed by the input XDP prog. |
| * @MARK_SKB: frame did hit the TC ingress hook as an skb. |
| */ |
| enum frame_mark { |
| MARK_XMIT = 0U, |
| MARK_IN = 0x42, |
| MARK_SKB = 0x45, |
| }; |
| |
| 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 != (__u32)ifindex_in) |
| return XDP_ABORTED; |
| |
| if (metadata + 1 > data) |
| return XDP_ABORTED; |
| |
| if (*metadata != 0x42) |
| return XDP_ABORTED; |
| |
| if (*payload == MARK_XMIT) |
| pkts_seen_zero++; |
| |
| *payload = MARK_IN; |
| |
| if (bpf_xdp_adjust_meta(xdp, sizeof(__u64))) |
| 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, const __u32 mark) |
| { |
| 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 != MARK_IN) |
| 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 = mark; |
| 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, MARK_XMIT)) |
| pkts_seen_xdp++; |
| |
| /* Return %XDP_DROP to recycle the data page with %MARK_XMIT, like |
| * it exited a physical NIC. Those 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, MARK_SKB)) |
| pkts_seen_tc++; |
| |
| /* Will be either recycled or freed, %MARK_SKB makes sure it won't |
| * hit any of the counters above. |
| */ |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |