1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com> 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of version 2 of the GNU General Public 6 * License as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, but 9 * WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 */ 13 14 #include <linux/bpf.h> 15 #include <linux/if_link.h> 16 #include <linux/limits.h> 17 #include <net/if.h> 18 #include <errno.h> 19 #include <stdio.h> 20 #include <stdlib.h> 21 #include <stdbool.h> 22 #include <string.h> 23 #include <unistd.h> 24 #include <fcntl.h> 25 #include <libgen.h> 26 27 #include <bpf/libbpf.h> 28 #include <bpf/bpf.h> 29 30 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; 31 32 static int do_attach(int idx, int prog_fd, int map_fd, const char *name) 33 { 34 int err; 35 36 err = bpf_set_link_xdp_fd(idx, prog_fd, xdp_flags); 37 if (err < 0) { 38 printf("ERROR: failed to attach program to %s\n", name); 39 return err; 40 } 41 42 /* Adding ifindex as a possible egress TX port */ 43 err = bpf_map_update_elem(map_fd, &idx, &idx, 0); 44 if (err) 45 printf("ERROR: failed using device %s as TX-port\n", name); 46 47 return err; 48 } 49 50 static int do_detach(int idx, const char *name) 51 { 52 int err; 53 54 err = bpf_set_link_xdp_fd(idx, -1, xdp_flags); 55 if (err < 0) 56 printf("ERROR: failed to detach program from %s\n", name); 57 58 /* TODO: Remember to cleanup map, when adding use of shared map 59 * bpf_map_delete_elem((map_fd, &idx); 60 */ 61 return err; 62 } 63 64 static void usage(const char *prog) 65 { 66 fprintf(stderr, 67 "usage: %s [OPTS] interface-list\n" 68 "\nOPTS:\n" 69 " -d detach program\n" 70 " -S use skb-mode\n" 71 " -F force loading prog\n" 72 " -D direct table lookups (skip fib rules)\n", 73 prog); 74 } 75 76 int main(int argc, char **argv) 77 { 78 struct bpf_prog_load_attr prog_load_attr = { 79 .prog_type = BPF_PROG_TYPE_XDP, 80 }; 81 const char *prog_name = "xdp_fwd"; 82 struct bpf_program *prog = NULL; 83 struct bpf_program *pos; 84 const char *sec_name; 85 int prog_fd, map_fd = -1; 86 char filename[PATH_MAX]; 87 struct bpf_object *obj; 88 int opt, i, idx, err; 89 int attach = 1; 90 int ret = 0; 91 92 while ((opt = getopt(argc, argv, ":dDSF")) != -1) { 93 switch (opt) { 94 case 'd': 95 attach = 0; 96 break; 97 case 'S': 98 xdp_flags |= XDP_FLAGS_SKB_MODE; 99 break; 100 case 'F': 101 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST; 102 break; 103 case 'D': 104 prog_name = "xdp_fwd_direct"; 105 break; 106 default: 107 usage(basename(argv[0])); 108 return 1; 109 } 110 } 111 112 if (!(xdp_flags & XDP_FLAGS_SKB_MODE)) 113 xdp_flags |= XDP_FLAGS_DRV_MODE; 114 115 if (optind == argc) { 116 usage(basename(argv[0])); 117 return 1; 118 } 119 120 if (attach) { 121 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); 122 prog_load_attr.file = filename; 123 124 if (access(filename, O_RDONLY) < 0) { 125 printf("error accessing file %s: %s\n", 126 filename, strerror(errno)); 127 return 1; 128 } 129 130 err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd); 131 if (err) { 132 printf("Does kernel support devmap lookup?\n"); 133 /* If not, the error message will be: 134 * "cannot pass map_type 14 into func bpf_map_lookup_elem#1" 135 */ 136 return 1; 137 } 138 139 bpf_object__for_each_program(pos, obj) { 140 sec_name = bpf_program__section_name(pos); 141 if (sec_name && !strcmp(sec_name, prog_name)) { 142 prog = pos; 143 break; 144 } 145 } 146 prog_fd = bpf_program__fd(prog); 147 if (prog_fd < 0) { 148 printf("program not found: %s\n", strerror(prog_fd)); 149 return 1; 150 } 151 map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj, 152 "xdp_tx_ports")); 153 if (map_fd < 0) { 154 printf("map not found: %s\n", strerror(map_fd)); 155 return 1; 156 } 157 } 158 159 for (i = optind; i < argc; ++i) { 160 idx = if_nametoindex(argv[i]); 161 if (!idx) 162 idx = strtoul(argv[i], NULL, 0); 163 164 if (!idx) { 165 fprintf(stderr, "Invalid arg\n"); 166 return 1; 167 } 168 if (!attach) { 169 err = do_detach(idx, argv[i]); 170 if (err) 171 ret = err; 172 } else { 173 err = do_attach(idx, prog_fd, map_fd, argv[i]); 174 if (err) 175 ret = err; 176 } 177 } 178 179 return ret; 180 } 181