cregit-Linux how code gets into the kernel

Release 4.10 samples/bpf/tcbpf1_kern.c

Directory: samples/bpf

#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_helpers.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); }

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#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); }

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#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); }

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#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); }

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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; }

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SEC("redirect_xmit")
int _redirect_xmit(struct __sk_buff *skb) { return bpf_redirect(skb->ifindex + 1, 0); }

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SEC("redirect_recv")
int _redirect_recv(struct __sk_buff *skb) { return bpf_redirect(skb->ifindex + 1, 1); }

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SEC("clone_redirect_xmit")
int _clone_redirect_xmit(struct __sk_buff *skb) { bpf_clone_redirect(skb, skb->ifindex + 1, 0); return TC_ACT_SHOT; }

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SEC("clone_redirect_recv")
int _clone_redirect_recv(struct __sk_buff *skb) { bpf_clone_redirect(skb, skb->ifindex + 1, 1); return TC_ACT_SHOT; }

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char _license[] SEC("license") = "GPL";

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daniel borkmanndaniel borkmann40.83%125.00%
Total480100.00%4100.00%
Directory: samples/bpf
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