92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
|
#define KBUILD_MODNAME "foo"
|
||
|
|
#include <uapi/linux/bpf.h>
|
||
|
|
#include <uapi/linux/if_ether.h>
|
||
|
|
#include <uapi/linux/if_packet.h>
|
||
|
|
#include <uapi/linux/ip.h>
|
||
|
|
#include <uapi/linux/in.h>
|
||
|
|
#include <uapi/linux/tcp.h>
|
||
|
|
#include <uapi/linux/filter.h>
|
||
|
|
#include <uapi/linux/pkt_cls.h>
|
||
|
|
#include <bpf/bpf_helpers.h>
|
||
|
|
#include "bpf_legacy.h"
|
||
|
|
|
||
|
|
/* compiler workaround */
|
||
|
|
#define _htonl __builtin_bswap32
|
||
|
|
|
||
|
|
static inline void set_dst_mac(struct __sk_buff *skb, char *mac)
|
||
|
|
{
|
||
|
|
bpf_skb_store_bytes(skb, 0, mac, ETH_ALEN, 1);
|
||
|
|
}
|
||
|
|
|
||
|
|
#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
|
||
|
|
#define TOS_OFF (ETH_HLEN + offsetof(struct iphdr, tos))
|
||
|
|
|
||
|
|
static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
|
||
|
|
{
|
||
|
|
__u8 old_tos = load_byte(skb, TOS_OFF);
|
||
|
|
|
||
|
|
bpf_l3_csum_replace(skb, IP_CSUM_OFF, htons(old_tos), htons(new_tos), 2);
|
||
|
|
bpf_skb_store_bytes(skb, TOS_OFF, &new_tos, sizeof(new_tos), 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
#define TCP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, check))
|
||
|
|
#define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr))
|
||
|
|
|
||
|
|
#define IS_PSEUDO 0x10
|
||
|
|
|
||
|
|
static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
|
||
|
|
{
|
||
|
|
__u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
|
||
|
|
|
||
|
|
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_ip, new_ip, IS_PSEUDO | sizeof(new_ip));
|
||
|
|
bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
|
||
|
|
bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
#define TCP_DPORT_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
|
||
|
|
static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
|
||
|
|
{
|
||
|
|
__u16 old_port = htons(load_half(skb, TCP_DPORT_OFF));
|
||
|
|
|
||
|
|
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_port, new_port, sizeof(new_port));
|
||
|
|
bpf_skb_store_bytes(skb, TCP_DPORT_OFF, &new_port, sizeof(new_port), 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
SEC("classifier")
|
||
|
|
int bpf_prog1(struct __sk_buff *skb)
|
||
|
|
{
|
||
|
|
__u8 proto = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
|
||
|
|
long *value;
|
||
|
|
|
||
|
|
if (proto == IPPROTO_TCP) {
|
||
|
|
set_ip_tos(skb, 8);
|
||
|
|
set_tcp_ip_src(skb, 0xA010101);
|
||
|
|
set_tcp_dest_port(skb, 5001);
|
||
|
|
}
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
SEC("redirect_xmit")
|
||
|
|
int _redirect_xmit(struct __sk_buff *skb)
|
||
|
|
{
|
||
|
|
return bpf_redirect(skb->ifindex + 1, 0);
|
||
|
|
}
|
||
|
|
SEC("redirect_recv")
|
||
|
|
int _redirect_recv(struct __sk_buff *skb)
|
||
|
|
{
|
||
|
|
return bpf_redirect(skb->ifindex + 1, 1);
|
||
|
|
}
|
||
|
|
SEC("clone_redirect_xmit")
|
||
|
|
int _clone_redirect_xmit(struct __sk_buff *skb)
|
||
|
|
{
|
||
|
|
bpf_clone_redirect(skb, skb->ifindex + 1, 0);
|
||
|
|
return TC_ACT_SHOT;
|
||
|
|
}
|
||
|
|
SEC("clone_redirect_recv")
|
||
|
|
int _clone_redirect_recv(struct __sk_buff *skb)
|
||
|
|
{
|
||
|
|
bpf_clone_redirect(skb, skb->ifindex + 1, 1);
|
||
|
|
return TC_ACT_SHOT;
|
||
|
|
}
|
||
|
|
char _license[] SEC("license") = "GPL";
|