xdp_fwd_user.c
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// 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/libbpf.h>
#include <bpf/bpf.h>
static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
{
int err;
err = bpf_set_link_xdp_fd(idx, prog_fd, xdp_flags);
if (err < 0) {
printf("ERROR: failed to attach program to %s\n", name);
return err;
}
/* Adding ifindex as a possible egress TX port */
err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
if (err)
printf("ERROR: failed using device %s as TX-port\n", name);
return err;
}
static int do_detach(int idx, const char *name)
{
int err;
err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
if (err < 0)
printf("ERROR: failed to detach program from %s\n", name);
/* TODO: Remember to cleanup map, when adding use of shared map
* bpf_map_delete_elem((map_fd, &idx);
*/
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)
{
struct bpf_prog_load_attr prog_load_attr = {
.prog_type = BPF_PROG_TYPE_XDP,
};
const char *prog_name = "xdp_fwd";
struct bpf_program *prog;
int prog_fd, map_fd = -1;
char filename[PATH_MAX];
struct bpf_object *obj;
int opt, i, idx, err;
int attach = 1;
int ret = 0;
while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
switch (opt) {
case 'd':
attach = 0;
break;
case 'S':
xdp_flags |= XDP_FLAGS_SKB_MODE;
break;
case 'F':
xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
break;
case 'D':
prog_name = "xdp_fwd_direct";
break;
default:
usage(basename(argv[0]));
return 1;
}
}
if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
xdp_flags |= XDP_FLAGS_DRV_MODE;
if (optind == argc) {
usage(basename(argv[0]));
return 1;
}
if (attach) {
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
prog_load_attr.file = filename;
if (access(filename, O_RDONLY) < 0) {
printf("error accessing file %s: %s\n",
filename, strerror(errno));
return 1;
}
err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
if (err) {
printf("Does kernel support devmap lookup?\n");
/* If not, the error message will be:
* "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
*/
return 1;
}
prog = bpf_object__find_program_by_title(obj, prog_name);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
printf("program not found: %s\n", strerror(prog_fd));
return 1;
}
map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
"xdp_tx_ports"));
if (map_fd < 0) {
printf("map not found: %s\n", strerror(map_fd));
return 1;
}
}
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, map_fd, argv[i]);
if (err)
ret = err;
}
}
return ret;
}