| // SPDX-License-Identifier: GPL-2.0 |
| #include <linux/bpf.h> |
| #include <bpf/bpf_endian.h> |
| #include <bpf/bpf_helpers.h> |
| #include <linux/ip.h> |
| #include "bpf_tracing_net.h" |
| |
| /* We don't care about whether the packet can be received by network stack. |
| * Just care if the packet is sent to the correct device at correct direction |
| * and not panic the kernel. |
| */ |
| static int prepend_dummy_mac(struct __sk_buff *skb) |
| { |
| char mac[] = {0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0xf, |
| 0xe, 0xd, 0xc, 0xb, 0xa, 0x08, 0x00}; |
| |
| if (bpf_skb_change_head(skb, ETH_HLEN, 0)) |
| return -1; |
| |
| if (bpf_skb_store_bytes(skb, 0, mac, sizeof(mac), 0)) |
| return -1; |
| |
| return 0; |
| } |
| |
| /* Use the last byte of IP address to redirect the packet */ |
| static int get_redirect_target(struct __sk_buff *skb) |
| { |
| struct iphdr *iph = NULL; |
| void *start = (void *)(long)skb->data; |
| void *end = (void *)(long)skb->data_end; |
| |
| if (start + sizeof(*iph) > end) |
| return -1; |
| |
| iph = (struct iphdr *)start; |
| return bpf_ntohl(iph->daddr) & 0xff; |
| } |
| |
| SEC("redir_ingress") |
| int test_lwt_redirect_in(struct __sk_buff *skb) |
| { |
| int target = get_redirect_target(skb); |
| |
| if (target < 0) |
| return BPF_OK; |
| |
| if (prepend_dummy_mac(skb)) |
| return BPF_DROP; |
| |
| return bpf_redirect(target, BPF_F_INGRESS); |
| } |
| |
| SEC("redir_egress") |
| int test_lwt_redirect_out(struct __sk_buff *skb) |
| { |
| int target = get_redirect_target(skb); |
| |
| if (target < 0) |
| return BPF_OK; |
| |
| if (prepend_dummy_mac(skb)) |
| return BPF_DROP; |
| |
| return bpf_redirect(target, 0); |
| } |
| |
| SEC("redir_egress_nomac") |
| int test_lwt_redirect_out_nomac(struct __sk_buff *skb) |
| { |
| int target = get_redirect_target(skb); |
| |
| if (target < 0) |
| return BPF_OK; |
| |
| return bpf_redirect(target, 0); |
| } |
| |
| SEC("redir_ingress_nomac") |
| int test_lwt_redirect_in_nomac(struct __sk_buff *skb) |
| { |
| int target = get_redirect_target(skb); |
| |
| if (target < 0) |
| return BPF_OK; |
| |
| return bpf_redirect(target, BPF_F_INGRESS); |
| } |
| |
| char _license[] SEC("license") = "GPL"; |