cregit-Linux how code gets into the kernel

Release 4.16 samples/bpf/tc_l2_redirect_kern.c

Directory: samples/bpf
/* Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */

#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/ipv6.h>
#include <uapi/linux/in.h>
#include <uapi/linux/tcp.h>
#include <uapi/linux/filter.h>
#include <uapi/linux/pkt_cls.h>
#include <net/ipv6.h>
#include "bpf_helpers.h"


#define _htonl __builtin_bswap32


#define PIN_GLOBAL_NS		2

struct bpf_elf_map {
	
__u32 type;
	
__u32 size_key;
	
__u32 size_value;
	
__u32 max_elem;
	
__u32 flags;
	
__u32 id;
	
__u32 pinning;
};

/* copy of 'struct ethhdr' without __packed */

struct eth_hdr {
	
unsigned char   h_dest[ETH_ALEN];
	
unsigned char   h_source[ETH_ALEN];
	
unsigned short  h_proto;
};

struct bpf_elf_map SEC("maps") tun_iface = {
	.type = BPF_MAP_TYPE_ARRAY,
	.size_key = sizeof(int),
	.size_value = sizeof(int),
	.pinning = PIN_GLOBAL_NS,
	.max_elem = 1,
};


static __always_inline bool is_vip_addr(__be16 eth_proto, __be32 daddr) { if (eth_proto == htons(ETH_P_IP)) return (_htonl(0xffffff00) & daddr) == _htonl(0x0a0a0100); else if (eth_proto == htons(ETH_P_IPV6)) return (daddr == _htonl(0x2401face)); return false; }

Contributors

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Martin KaFai Lau60100.00%1100.00%
Total60100.00%1100.00%

SEC("l2_to_iptun_ingress_forward")
int _l2_to_iptun_ingress_forward(struct __sk_buff *skb) { struct bpf_tunnel_key tkey = {}; void *data = (void *)(long)skb->data; struct eth_hdr *eth = data; void *data_end = (void *)(long)skb->data_end; int key = 0, *ifindex; int ret; if (data + sizeof(*eth) > data_end) return TC_ACT_OK; ifindex = bpf_map_lookup_elem(&tun_iface, &key); if (!ifindex) return TC_ACT_OK; if (eth->h_proto == htons(ETH_P_IP)) { char fmt4[] = "ingress forward to ifindex:%d daddr4:%x\n"; struct iphdr *iph = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*iph) > data_end) return TC_ACT_OK; if (iph->protocol != IPPROTO_IPIP) return TC_ACT_OK; bpf_trace_printk(fmt4, sizeof(fmt4), *ifindex, _htonl(iph->daddr)); return bpf_redirect(*ifindex, BPF_F_INGRESS); } else if (eth->h_proto == htons(ETH_P_IPV6)) { char fmt6[] = "ingress forward to ifindex:%d daddr6:%x::%x\n"; struct ipv6hdr *ip6h = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*ip6h) > data_end) return TC_ACT_OK; if (ip6h->nexthdr != IPPROTO_IPIP && ip6h->nexthdr != IPPROTO_IPV6) return TC_ACT_OK; bpf_trace_printk(fmt6, sizeof(fmt6), *ifindex, _htonl(ip6h->daddr.s6_addr32[0]), _htonl(ip6h->daddr.s6_addr32[3])); return bpf_redirect(*ifindex, BPF_F_INGRESS); } return TC_ACT_OK; }

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Martin KaFai Lau311100.00%1100.00%
Total311100.00%1100.00%

SEC("l2_to_iptun_ingress_redirect")
int _l2_to_iptun_ingress_redirect(struct __sk_buff *skb) { struct bpf_tunnel_key tkey = {}; void *data = (void *)(long)skb->data; struct eth_hdr *eth = data; void *data_end = (void *)(long)skb->data_end; int key = 0, *ifindex; int ret; if (data + sizeof(*eth) > data_end) return TC_ACT_OK; ifindex = bpf_map_lookup_elem(&tun_iface, &key); if (!ifindex) return TC_ACT_OK; if (eth->h_proto == htons(ETH_P_IP)) { char fmt4[] = "e/ingress redirect daddr4:%x to ifindex:%d\n"; struct iphdr *iph = data + sizeof(*eth); __be32 daddr = iph->daddr; if (data + sizeof(*eth) + sizeof(*iph) > data_end) return TC_ACT_OK; if (!is_vip_addr(eth->h_proto, daddr)) return TC_ACT_OK; bpf_trace_printk(fmt4, sizeof(fmt4), _htonl(daddr), *ifindex); } else { return TC_ACT_OK; } tkey.tunnel_id = 10000; tkey.tunnel_ttl = 64; tkey.remote_ipv4 = 0x0a020166; /* 10.2.1.102 */ bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), 0); return bpf_redirect(*ifindex, 0); }

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Martin KaFai Lau240100.00%1100.00%
Total240100.00%1100.00%

SEC("l2_to_ip6tun_ingress_redirect")
int _l2_to_ip6tun_ingress_redirect(struct __sk_buff *skb) { struct bpf_tunnel_key tkey = {}; void *data = (void *)(long)skb->data; struct eth_hdr *eth = data; void *data_end = (void *)(long)skb->data_end; int key = 0, *ifindex; if (data + sizeof(*eth) > data_end) return TC_ACT_OK; ifindex = bpf_map_lookup_elem(&tun_iface, &key); if (!ifindex) return TC_ACT_OK; if (eth->h_proto == htons(ETH_P_IP)) { char fmt4[] = "e/ingress redirect daddr4:%x to ifindex:%d\n"; struct iphdr *iph = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*iph) > data_end) return TC_ACT_OK; if (!is_vip_addr(eth->h_proto, iph->daddr)) return TC_ACT_OK; bpf_trace_printk(fmt4, sizeof(fmt4), _htonl(iph->daddr), *ifindex); } else if (eth->h_proto == htons(ETH_P_IPV6)) { char fmt6[] = "e/ingress redirect daddr6:%x to ifindex:%d\n"; struct ipv6hdr *ip6h = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*ip6h) > data_end) return TC_ACT_OK; if (!is_vip_addr(eth->h_proto, ip6h->daddr.s6_addr32[0])) return TC_ACT_OK; bpf_trace_printk(fmt6, sizeof(fmt6), _htonl(ip6h->daddr.s6_addr32[0]), *ifindex); } else { return TC_ACT_OK; } tkey.tunnel_id = 10000; tkey.tunnel_ttl = 64; /* 2401:db02:0:0:0:0:0:66 */ tkey.remote_ipv6[0] = _htonl(0x2401db02); tkey.remote_ipv6[1] = 0; tkey.remote_ipv6[2] = 0; tkey.remote_ipv6[3] = _htonl(0x00000066); bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), BPF_F_TUNINFO_IPV6); return bpf_redirect(*ifindex, 0); }

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Martin KaFai Lau371100.00%1100.00%
Total371100.00%1100.00%

SEC("drop_non_tun_vip")
int _drop_non_tun_vip(struct __sk_buff *skb) { struct bpf_tunnel_key tkey = {}; void *data = (void *)(long)skb->data; struct eth_hdr *eth = data; void *data_end = (void *)(long)skb->data_end; if (data + sizeof(*eth) > data_end) return TC_ACT_OK; if (eth->h_proto == htons(ETH_P_IP)) { struct iphdr *iph = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*iph) > data_end) return TC_ACT_OK; if (is_vip_addr(eth->h_proto, iph->daddr)) return TC_ACT_SHOT; } else if (eth->h_proto == htons(ETH_P_IPV6)) { struct ipv6hdr *ip6h = data + sizeof(*eth); if (data + sizeof(*eth) + sizeof(*ip6h) > data_end) return TC_ACT_OK; if (is_vip_addr(eth->h_proto, ip6h->daddr.s6_addr32[0])) return TC_ACT_SHOT; } return TC_ACT_OK; }

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Martin KaFai Lau203100.00%1100.00%
Total203100.00%1100.00%

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

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Martin KaFai Lau134499.70%150.00%
Jesper Dangaard Brouer40.30%150.00%
Total1348100.00%2100.00%
Directory: samples/bpf
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