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