cregit-Linux how code gets into the kernel

Release 4.14 samples/bpf/xdp1_kern.c

Directory: samples/bpf
/* Copyright (c) 2016 PLUMgrid
 *
 * 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 <linux/in.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include "bpf_helpers.h"

struct bpf_map_def SEC("maps") rxcnt = {
	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
	.key_size = sizeof(u32),
	.value_size = sizeof(long),
	.max_entries = 256,
};


static int parse_ipv4(void *data, u64 nh_off, void *data_end) { struct iphdr *iph = data + nh_off; if (iph + 1 > data_end) return 0; return iph->protocol; }

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static int parse_ipv6(void *data, u64 nh_off, void *data_end) { struct ipv6hdr *ip6h = data + nh_off; if (ip6h + 1 > data_end) return 0; return ip6h->nexthdr; }

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SEC("xdp1")
int xdp_prog1(struct xdp_md *ctx) { void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; struct ethhdr *eth = data; int rc = XDP_DROP; long *value; u16 h_proto; u64 nh_off; u32 ipproto; nh_off = sizeof(*eth); if (data + nh_off > data_end) return rc; h_proto = eth->h_proto; if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return rc; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return rc; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == htons(ETH_P_IP)) ipproto = parse_ipv4(data, nh_off, data_end); else if (h_proto == htons(ETH_P_IPV6)) ipproto = parse_ipv6(data, nh_off, data_end); else ipproto = 0; value = bpf_map_lookup_elem(&rxcnt, &ipproto); if (value) *value += 1; return rc; }

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

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Directory: samples/bpf
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