samples/bpf: Add example of ipv4 and ipv6 forwarding in XDP (fe616055) · Commits · 戴 / test

samples/bpf/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -46,6 +46,7 @@ hostprogs-y += syscall_tp
		hostprogs-y += cpustat
		hostprogs-y += xdp_adjust_tail
		hostprogs-y += xdpsock
		hostprogs-y += xdp_fwd

		# Libbpf dependencies
		LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o
		@@ -100,6 +101,7 @@ syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
		cpustat-objs := bpf_load.o $(LIBBPF) cpustat_user.o
		xdp_adjust_tail-objs := bpf_load.o $(LIBBPF) xdp_adjust_tail_user.o
		xdpsock-objs := bpf_load.o $(LIBBPF) xdpsock_user.o
		xdp_fwd-objs := bpf_load.o $(LIBBPF) xdp_fwd_user.o

		# Tell kbuild to always build the programs
		always := $(hostprogs-y)
		@@ -154,6 +156,7 @@ always += syscall_tp_kern.o
		always += cpustat_kern.o
		always += xdp_adjust_tail_kern.o
		always += xdpsock_kern.o
		always += xdp_fwd_kern.o

		HOSTCFLAGS += -I$(objtree)/usr/include
		HOSTCFLAGS += -I$(srctree)/tools/lib/
		@@ -201,6 +204,7 @@ HOSTLOADLIBES_syscall_tp += -lelf
		HOSTLOADLIBES_cpustat += -lelf
		HOSTLOADLIBES_xdp_adjust_tail += -lelf
		HOSTLOADLIBES_xdpsock += -lelf -pthread
		HOSTLOADLIBES_xdp_fwd += -lelf

		# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
		# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

samples/bpf/xdp_fwd_kern.c

0 → 100644

+115 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.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"

		#define IPV6_FLOWINFO_MASK cpu_to_be32(0x0FFFFFFF)

		struct bpf_map_def SEC("maps") tx_port = {
		.type = BPF_MAP_TYPE_DEVMAP,
		.key_size = sizeof(int),
		.value_size = sizeof(int),
		.max_entries = 64,
		};

		static __always_inline int xdp_fwd_flags(struct xdp_md *ctx, u32 flags)
		{
		void data_end = (void )(long)ctx->data_end;
		void data = (void )(long)ctx->data;
		struct bpf_fib_lookup fib_params;
		struct ethhdr *eth = data;
		int out_index;
		u16 h_proto;
		u64 nh_off;

		nh_off = sizeof(*eth);
		if (data + nh_off > data_end)
		return XDP_DROP;

		__builtin_memset(&fib_params, 0, sizeof(fib_params));

		h_proto = eth->h_proto;
		if (h_proto == htons(ETH_P_IP)) {
		struct iphdr *iph = data + nh_off;

		if (iph + 1 > data_end)
		return XDP_DROP;

		fib_params.family = AF_INET;
		fib_params.tos = iph->tos;
		fib_params.l4_protocol = iph->protocol;
		fib_params.sport = 0;
		fib_params.dport = 0;
		fib_params.tot_len = ntohs(iph->tot_len);
		fib_params.ipv4_src = iph->saddr;
		fib_params.ipv4_dst = iph->daddr;
		} else if (h_proto == htons(ETH_P_IPV6)) {
		struct in6_addr src = (struct in6_addr ) fib_params.ipv6_src;
		struct in6_addr dst = (struct in6_addr ) fib_params.ipv6_dst;
		struct ipv6hdr *iph = data + nh_off;

		if (iph + 1 > data_end)
		return XDP_DROP;

		fib_params.family = AF_INET6;
		fib_params.flowlabel = (__be32 )iph & IPV6_FLOWINFO_MASK;
		fib_params.l4_protocol = iph->nexthdr;
		fib_params.sport = 0;
		fib_params.dport = 0;
		fib_params.tot_len = ntohs(iph->payload_len);
		*src = iph->saddr;
		*dst = iph->daddr;
		} else {
		return XDP_PASS;
		}

		fib_params.ifindex = ctx->ingress_ifindex;

		out_index = bpf_fib_lookup(ctx, &fib_params, sizeof(fib_params), flags);

		/* verify egress index has xdp support
		* TO-DO bpf_map_lookup_elem(&tx_port, &key) fails with
		* cannot pass map_type 14 into func bpf_map_lookup_elem#1:
		* NOTE: without verification that egress index supports XDP
		* forwarding packets are dropped.
		*/
		if (out_index > 0) {
		memcpy(eth->h_dest, fib_params.dmac, ETH_ALEN);
		memcpy(eth->h_source, fib_params.smac, ETH_ALEN);
		return bpf_redirect_map(&tx_port, out_index, 0);
		}

		return XDP_PASS;
		}

		SEC("xdp_fwd")
		int xdp_fwd_prog(struct xdp_md *ctx)
		{
		return xdp_fwd_flags(ctx, 0);
		}

		SEC("xdp_fwd_direct")
		int xdp_fwd_direct_prog(struct xdp_md *ctx)
		{
		return xdp_fwd_flags(ctx, BPF_FIB_LOOKUP_DIRECT);
		}

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

samples/bpf/xdp_fwd_user.c

0 → 100644

+136 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.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.
		*/

		#include <linux/bpf.h>
		#include <linux/if_link.h>
		#include <linux/limits.h>
		#include <net/if.h>
		#include <errno.h>
		#include <stdio.h>
		#include <stdlib.h>
		#include <stdbool.h>
		#include <string.h>
		#include <unistd.h>
		#include <fcntl.h>
		#include <libgen.h>

		#include "bpf_load.h"
		#include "bpf_util.h"
		#include "libbpf.h"


		static int do_attach(int idx, int fd, const char *name)
		{
		int err;

		err = bpf_set_link_xdp_fd(idx, fd, 0);
		if (err < 0)
		printf("ERROR: failed to attach program to %s\n", name);

		return err;
		}

		static int do_detach(int idx, const char *name)
		{
		int err;

		err = bpf_set_link_xdp_fd(idx, -1, 0);
		if (err < 0)
		printf("ERROR: failed to detach program from %s\n", name);

		return err;
		}

		static void usage(const char *prog)
		{
		fprintf(stderr,
		"usage: %s [OPTS] interface-list\n"
		"\nOPTS:\n"
		" -d detach program\n"
		" -D direct table lookups (skip fib rules)\n",
		prog);
		}

		int main(int argc, char **argv)
		{
		char filename[PATH_MAX];
		int opt, i, idx, err;
		int prog_id = 0;
		int attach = 1;
		int ret = 0;

		while ((opt = getopt(argc, argv, ":dD")) != -1) {
		switch (opt) {
		case 'd':
		attach = 0;
		break;
		case 'D':
		prog_id = 1;
		break;
		default:
		usage(basename(argv[0]));
		return 1;
		}
		}

		if (optind == argc) {
		usage(basename(argv[0]));
		return 1;
		}

		if (attach) {
		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);

		if (access(filename, O_RDONLY) < 0) {
		printf("error accessing file %s: %s\n",
		filename, strerror(errno));
		return 1;
		}

		if (load_bpf_file(filename)) {
		printf("%s", bpf_log_buf);
		return 1;
		}

		if (!prog_fd[prog_id]) {
		printf("load_bpf_file: %s\n", strerror(errno));
		return 1;
		}
		}
		if (attach) {
		for (i = 1; i < 64; ++i)
		bpf_map_update_elem(map_fd[0], &i, &i, 0);
		}

		for (i = optind; i < argc; ++i) {
		idx = if_nametoindex(argv[i]);
		if (!idx)
		idx = strtoul(argv[i], NULL, 0);

		if (!idx) {
		fprintf(stderr, "Invalid arg\n");
		return 1;
		}
		if (!attach) {
		err = do_detach(idx, argv[i]);
		if (err)
		ret = err;
		} else {
		err = do_attach(idx, prog_fd[prog_id], argv[i]);
		if (err)
		ret = err;
		}
		}

		return ret;
		}

tools/testing/selftests/bpf/bpf_helpers.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -103,6 +103,9 @@ static int (bpf_skb_get_xfrm_state)(void ctx, int index, void *state,
		(void *) BPF_FUNC_skb_get_xfrm_state;
		static int (bpf_get_stack)(void ctx, void *buf, int size, int flags) =
		(void *) BPF_FUNC_get_stack;
		static int (bpf_fib_lookup)(void ctx, struct bpf_fib_lookup *params,
		int plen, __u32 flags) =
		(void *) BPF_FUNC_fib_lookup;

		/* llvm builtin functions that eBPF C program may use to
		* emit BPF_LD_ABS and BPF_LD_IND instructions

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