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
do_attach(int idx,int prog_fd,int map_fd,const char * name)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
do_detach(int idx,const char * name)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
usage(const char * prog)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 " -D direct table lookups (skip fib rules)\n",
71 prog);
72 }
73
main(int argc,char ** argv)74 int main(int argc, char **argv)
75 {
76 struct bpf_prog_load_attr prog_load_attr = {
77 .prog_type = BPF_PROG_TYPE_XDP,
78 };
79 const char *prog_name = "xdp_fwd";
80 struct bpf_program *prog;
81 int prog_fd, map_fd = -1;
82 char filename[PATH_MAX];
83 struct bpf_object *obj;
84 int opt, i, idx, err;
85 int attach = 1;
86 int ret = 0;
87
88 while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
89 switch (opt) {
90 case 'd':
91 attach = 0;
92 break;
93 case 'S':
94 xdp_flags |= XDP_FLAGS_SKB_MODE;
95 break;
96 case 'F':
97 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
98 break;
99 case 'D':
100 prog_name = "xdp_fwd_direct";
101 break;
102 default:
103 usage(basename(argv[0]));
104 return 1;
105 }
106 }
107
108 if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
109 xdp_flags |= XDP_FLAGS_DRV_MODE;
110
111 if (optind == argc) {
112 usage(basename(argv[0]));
113 return 1;
114 }
115
116 if (attach) {
117 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
118 prog_load_attr.file = filename;
119
120 if (access(filename, O_RDONLY) < 0) {
121 printf("error accessing file %s: %s\n",
122 filename, strerror(errno));
123 return 1;
124 }
125
126 err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
127 if (err) {
128 printf("Does kernel support devmap lookup?\n");
129 /* If not, the error message will be:
130 * "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
131 */
132 return 1;
133 }
134
135 prog = bpf_object__find_program_by_title(obj, prog_name);
136 prog_fd = bpf_program__fd(prog);
137 if (prog_fd < 0) {
138 printf("program not found: %s\n", strerror(prog_fd));
139 return 1;
140 }
141 map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
142 "xdp_tx_ports"));
143 if (map_fd < 0) {
144 printf("map not found: %s\n", strerror(map_fd));
145 return 1;
146 }
147 }
148
149 for (i = optind; i < argc; ++i) {
150 idx = if_nametoindex(argv[i]);
151 if (!idx)
152 idx = strtoul(argv[i], NULL, 0);
153
154 if (!idx) {
155 fprintf(stderr, "Invalid arg\n");
156 return 1;
157 }
158 if (!attach) {
159 err = do_detach(idx, argv[i]);
160 if (err)
161 ret = err;
162 } else {
163 err = do_attach(idx, prog_fd, map_fd, argv[i]);
164 if (err)
165 ret = err;
166 }
167 }
168
169 return ret;
170 }
171
