1// SPDX-License-Identifier: GPL-2.0 2#include <linux/bpf.h> 3#include <bpf/bpf_endian.h> 4#include <bpf/bpf_helpers.h> 5#include <linux/ip.h> 6#include "bpf_tracing_net.h" 7 8/* We don't care about whether the packet can be received by network stack. 9 * Just care if the packet is sent to the correct device at correct direction 10 * and not panic the kernel. 11 */ 12static int prepend_dummy_mac(struct __sk_buff *skb) 13{ 14 char mac[] = {0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0xf, 15 0xe, 0xd, 0xc, 0xb, 0xa, 0x08, 0x00}; 16 17 if (bpf_skb_change_head(skb, ETH_HLEN, 0)) 18 return -1; 19 20 if (bpf_skb_store_bytes(skb, 0, mac, sizeof(mac), 0)) 21 return -1; 22 23 return 0; 24} 25 26/* Use the last byte of IP address to redirect the packet */ 27static int get_redirect_target(struct __sk_buff *skb) 28{ 29 struct iphdr *iph = NULL; 30 void *start = (void *)(long)skb->data; 31 void *end = (void *)(long)skb->data_end; 32 33 if (start + sizeof(*iph) > end) 34 return -1; 35 36 iph = (struct iphdr *)start; 37 return bpf_ntohl(iph->daddr) & 0xff; 38} 39 40SEC("redir_ingress") 41int test_lwt_redirect_in(struct __sk_buff *skb) 42{ 43 int target = get_redirect_target(skb); 44 45 if (target < 0) 46 return BPF_OK; 47 48 if (prepend_dummy_mac(skb)) 49 return BPF_DROP; 50 51 return bpf_redirect(target, BPF_F_INGRESS); 52} 53 54SEC("redir_egress") 55int test_lwt_redirect_out(struct __sk_buff *skb) 56{ 57 int target = get_redirect_target(skb); 58 59 if (target < 0) 60 return BPF_OK; 61 62 if (prepend_dummy_mac(skb)) 63 return BPF_DROP; 64 65 return bpf_redirect(target, 0); 66} 67 68SEC("redir_egress_nomac") 69int test_lwt_redirect_out_nomac(struct __sk_buff *skb) 70{ 71 int target = get_redirect_target(skb); 72 73 if (target < 0) 74 return BPF_OK; 75 76 return bpf_redirect(target, 0); 77} 78 79SEC("redir_ingress_nomac") 80int test_lwt_redirect_in_nomac(struct __sk_buff *skb) 81{ 82 int target = get_redirect_target(skb); 83 84 if (target < 0) 85 return BPF_OK; 86 87 return bpf_redirect(target, BPF_F_INGRESS); 88} 89 90char _license[] SEC("license") = "GPL"; 91