cregit-Linux how code gets into the kernel

Release 4.14 samples/bpf/xdp_redirect_kern.c

Directory: samples/bpf
/* Copyright (c) 2016 John Fastabend <john.r.fastabend@intel.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */

#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") tx_port = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 1,
};

/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
 * feedback.  Redirect TX errors can be caught via a tracepoint.
 */
struct bpf_map_def SEC("maps") rxcnt = {
	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
	.key_size = sizeof(u32),
	.value_size = sizeof(long),
	.max_entries = 1,
};


static void swap_src_dst_mac(void *data) { unsigned short *p = data; unsigned short dst[3]; dst[0] = p[0]; dst[1] = p[1]; dst[2] = p[2]; p[0] = p[3]; p[1] = p[4]; p[2] = p[5]; p[3] = dst[0]; p[4] = dst[1]; p[5] = dst[2]; }

Contributors

PersonTokensPropCommitsCommitProp
John Fastabend114100.00%1100.00%
Total114100.00%1100.00%

SEC("xdp_redirect")
int xdp_redirect_prog(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; int *ifindex, port = 0; long *value; u32 key = 0; u64 nh_off; nh_off = sizeof(*eth); if (data + nh_off > data_end) return rc; ifindex = bpf_map_lookup_elem(&tx_port, &port); if (!ifindex) return rc; value = bpf_map_lookup_elem(&rxcnt, &key); if (value) *value += 1; swap_src_dst_mac(data); return bpf_redirect(*ifindex, 0); }

Contributors

PersonTokensPropCommitsCommitProp
John Fastabend144100.00%1100.00%
Total144100.00%1100.00%

/* Redirect require an XDP bpf_prog loaded on the TX device */ SEC("xdp_redirect_dummy")
int xdp_redirect_dummy_prog(struct xdp_md *ctx) { return XDP_PASS; }

Contributors

PersonTokensPropCommitsCommitProp
Jesper Dangaard Brouer1292.31%150.00%
Tariq Toukan17.69%150.00%
Total13100.00%2100.00%

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

Overall Contributors

PersonTokensPropCommitsCommitProp
John Fastabend37395.15%133.33%
Jesper Dangaard Brouer184.59%133.33%
Tariq Toukan10.26%133.33%
Total392100.00%3100.00%
Directory: samples/bpf
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