blob: 9bfb2eb34563d0158dae21c97c1b37d640e8d62a [file] [log] [blame]
Alexei Starovoitov91bc48222015-04-01 17:12:13 -07001#include <uapi/linux/bpf.h>
2#include <uapi/linux/if_ether.h>
3#include <uapi/linux/if_packet.h>
4#include <uapi/linux/ip.h>
5#include <uapi/linux/in.h>
6#include <uapi/linux/tcp.h>
Alexei Starovoitova1661512015-04-15 12:55:45 -07007#include <uapi/linux/filter.h>
8
Alexei Starovoitov91bc48222015-04-01 17:12:13 -07009#include "bpf_helpers.h"
10
11/* compiler workaround */
12#define _htonl __builtin_bswap32
13
14static inline void set_dst_mac(struct __sk_buff *skb, char *mac)
15{
16 bpf_skb_store_bytes(skb, 0, mac, ETH_ALEN, 1);
17}
18
Alexei Starovoitov91bc48222015-04-01 17:12:13 -070019#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
20#define TOS_OFF (ETH_HLEN + offsetof(struct iphdr, tos))
21
22static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
23{
Alexei Starovoitov34312052015-06-04 10:11:53 -070024 __u8 old_tos = load_byte(skb, TOS_OFF);
Alexei Starovoitov91bc48222015-04-01 17:12:13 -070025
26 bpf_l3_csum_replace(skb, IP_CSUM_OFF, htons(old_tos), htons(new_tos), 2);
27 bpf_skb_store_bytes(skb, TOS_OFF, &new_tos, sizeof(new_tos), 0);
28}
29
30#define TCP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, check))
31#define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr))
32
33#define IS_PSEUDO 0x10
34
35static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
36{
Alexei Starovoitov34312052015-06-04 10:11:53 -070037 __u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
Alexei Starovoitov91bc48222015-04-01 17:12:13 -070038
39 bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_ip, new_ip, IS_PSEUDO | sizeof(new_ip));
40 bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
41 bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
42}
43
44#define TCP_DPORT_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
45static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
46{
Alexei Starovoitov34312052015-06-04 10:11:53 -070047 __u16 old_port = htons(load_half(skb, TCP_DPORT_OFF));
Alexei Starovoitov91bc48222015-04-01 17:12:13 -070048
49 bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_port, new_port, sizeof(new_port));
50 bpf_skb_store_bytes(skb, TCP_DPORT_OFF, &new_port, sizeof(new_port), 0);
51}
52
53SEC("classifier")
54int bpf_prog1(struct __sk_buff *skb)
55{
Alexei Starovoitov34312052015-06-04 10:11:53 -070056 __u8 proto = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
Alexei Starovoitov91bc48222015-04-01 17:12:13 -070057 long *value;
58
59 if (proto == IPPROTO_TCP) {
60 set_ip_tos(skb, 8);
61 set_tcp_ip_src(skb, 0xA010101);
62 set_tcp_dest_port(skb, 5001);
63 }
64
65 return 0;
66}
67char _license[] SEC("license") = "GPL";