Commit fe616055 authored by David Ahern's avatar David Ahern Committed by Daniel Borkmann

samples/bpf: Add example of ipv4 and ipv6 forwarding in XDP

Simple example of fast-path forwarding. It has a serious flaw
in not verifying the egress device index supports XDP forwarding.
If the egress device does not packets are dropped.

Take this only as a simple example of fast-path forwarding.
Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 87f5fc7e
......@@ -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
......
// 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";
// 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;
}
......@@ -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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