1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
// SPDX-License-Identifier: GPL-2.0
#include <stdint.h>
#include <stdbool.h>
#include <linux/bpf.h>
#include <linux/stddef.h>
#include <linux/pkt_cls.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#ifndef ctx_ptr
# define ctx_ptr(field) (void *)(long)(field)
#endif
#define ip4_src 0xac100164 /* 172.16.1.100 */
#define ip4_dst 0xac100264 /* 172.16.2.100 */
#define ip6_src { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
0x00, 0x01, 0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe }
#define ip6_dst { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
0x00, 0x02, 0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe }
#ifndef v6_equal
# define v6_equal(a, b) (a.s6_addr32[0] == b.s6_addr32[0] && \
a.s6_addr32[1] == b.s6_addr32[1] && \
a.s6_addr32[2] == b.s6_addr32[2] && \
a.s6_addr32[3] == b.s6_addr32[3])
#endif
enum {
dev_src,
dev_dst,
};
struct bpf_map_def SEC("maps") ifindex_map = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 2,
};
static __always_inline bool is_remote_ep_v4(struct __sk_buff *skb,
__be32 addr)
{
void *data_end = ctx_ptr(skb->data_end);
void *data = ctx_ptr(skb->data);
struct iphdr *ip4h;
if (data + sizeof(struct ethhdr) > data_end)
return false;
ip4h = (struct iphdr *)(data + sizeof(struct ethhdr));
if ((void *)(ip4h + 1) > data_end)
return false;
return ip4h->daddr == addr;
}
static __always_inline bool is_remote_ep_v6(struct __sk_buff *skb,
struct in6_addr addr)
{
void *data_end = ctx_ptr(skb->data_end);
void *data = ctx_ptr(skb->data);
struct ipv6hdr *ip6h;
if (data + sizeof(struct ethhdr) > data_end)
return false;
ip6h = (struct ipv6hdr *)(data + sizeof(struct ethhdr));
if ((void *)(ip6h + 1) > data_end)
return false;
return v6_equal(ip6h->daddr, addr);
}
static __always_inline int get_dev_ifindex(int which)
{
int *ifindex = bpf_map_lookup_elem(&ifindex_map, &which);
return ifindex ? *ifindex : 0;
}
SEC("chk_egress") int tc_chk(struct __sk_buff *skb)
{
void *data_end = ctx_ptr(skb->data_end);
void *data = ctx_ptr(skb->data);
__u32 *raw = data;
if (data + sizeof(struct ethhdr) > data_end)
return TC_ACT_SHOT;
return !raw[0] && !raw[1] && !raw[2] ? TC_ACT_SHOT : TC_ACT_OK;
}
SEC("dst_ingress") int tc_dst(struct __sk_buff *skb)
{
__u8 zero[ETH_ALEN * 2];
bool redirect = false;
switch (skb->protocol) {
case __bpf_constant_htons(ETH_P_IP):
redirect = is_remote_ep_v4(skb, __bpf_constant_htonl(ip4_src));
break;
case __bpf_constant_htons(ETH_P_IPV6):
redirect = is_remote_ep_v6(skb, (struct in6_addr)ip6_src);
break;
}
if (!redirect)
return TC_ACT_OK;
__builtin_memset(&zero, 0, sizeof(zero));
if (bpf_skb_store_bytes(skb, 0, &zero, sizeof(zero), 0) < 0)
return TC_ACT_SHOT;
return bpf_redirect_neigh(get_dev_ifindex(dev_src), 0);
}
SEC("src_ingress") int tc_src(struct __sk_buff *skb)
{
__u8 zero[ETH_ALEN * 2];
bool redirect = false;
switch (skb->protocol) {
case __bpf_constant_htons(ETH_P_IP):
redirect = is_remote_ep_v4(skb, __bpf_constant_htonl(ip4_dst));
break;
case __bpf_constant_htons(ETH_P_IPV6):
redirect = is_remote_ep_v6(skb, (struct in6_addr)ip6_dst);
break;
}
if (!redirect)
return TC_ACT_OK;
__builtin_memset(&zero, 0, sizeof(zero));
if (bpf_skb_store_bytes(skb, 0, &zero, sizeof(zero), 0) < 0)
return TC_ACT_SHOT;
return bpf_redirect_neigh(get_dev_ifindex(dev_dst), 0);
}
char __license[] SEC("license") = "GPL";
|
