samples/bpf/xdp_fwd_user.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com>
0003  *
0004  * This program is free software; you can redistribute it and/or
0005  * modify it under the terms of version 2 of the GNU General Public
0006  * License as published by the Free Software Foundation.
0007  *
0008  * This program is distributed in the hope that it will be useful, but
0009  * WITHOUT ANY WARRANTY; without even the implied warranty of
0010  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
0011  * General Public License for more details.
0012  */
0013
0014 #include <linux/bpf.h>
0015 #include <linux/if_link.h>
0016 #include <linux/limits.h>
0017 #include <net/if.h>
0018 #include <errno.h>
0019 #include <stdio.h>
0020 #include <stdlib.h>
0021 #include <stdbool.h>
0022 #include <string.h>
0023 #include <unistd.h>
0024 #include <fcntl.h>
0025 #include <libgen.h>
0026
0027 #include <bpf/libbpf.h>
0028 #include <bpf/bpf.h>
0029
0030 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
0031
0032 static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
0033 {
0034     int err;
0035
0036     err = bpf_xdp_attach(idx, prog_fd, xdp_flags, NULL);
0037     if (err < 0) {
0038         printf("ERROR: failed to attach program to %s\n", name);
0039         return err;
0040     }
0041
0042     /* Adding ifindex as a possible egress TX port */
0043     err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
0044     if (err)
0045         printf("ERROR: failed using device %s as TX-port\n", name);
0046
0047     return err;
0048 }
0049
0050 static int do_detach(int ifindex, const char *ifname, const char *app_name)
0051 {
0052     LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
0053     struct bpf_prog_info prog_info = {};
0054     char prog_name[BPF_OBJ_NAME_LEN];
0055     __u32 info_len, curr_prog_id;
0056     int prog_fd;
0057     int err = 1;
0058
0059     if (bpf_xdp_query_id(ifindex, xdp_flags, &curr_prog_id)) {
0060         printf("ERROR: bpf_xdp_query_id failed (%s)\n",
0061                strerror(errno));
0062         return err;
0063     }
0064
0065     if (!curr_prog_id) {
0066         printf("ERROR: flags(0x%x) xdp prog is not attached to %s\n",
0067                xdp_flags, ifname);
0068         return err;
0069     }
0070
0071     info_len = sizeof(prog_info);
0072     prog_fd = bpf_prog_get_fd_by_id(curr_prog_id);
0073     if (prog_fd < 0) {
0074         printf("ERROR: bpf_prog_get_fd_by_id failed (%s)\n",
0075                strerror(errno));
0076         return prog_fd;
0077     }
0078
0079     err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
0080     if (err) {
0081         printf("ERROR: bpf_obj_get_info_by_fd failed (%s)\n",
0082                strerror(errno));
0083         goto close_out;
0084     }
0085     snprintf(prog_name, sizeof(prog_name), "%s_prog", app_name);
0086     prog_name[BPF_OBJ_NAME_LEN - 1] = '\0';
0087
0088     if (strcmp(prog_info.name, prog_name)) {
0089         printf("ERROR: %s isn't attached to %s\n", app_name, ifname);
0090         err = 1;
0091         goto close_out;
0092     }
0093
0094     opts.old_prog_fd = prog_fd;
0095     err = bpf_xdp_detach(ifindex, xdp_flags, &opts);
0096     if (err < 0)
0097         printf("ERROR: failed to detach program from %s (%s)\n",
0098                ifname, strerror(errno));
0099     /* TODO: Remember to cleanup map, when adding use of shared map
0100      *  bpf_map_delete_elem((map_fd, &idx);
0101      */
0102 close_out:
0103     close(prog_fd);
0104     return err;
0105 }
0106
0107 static void usage(const char *prog)
0108 {
0109     fprintf(stderr,
0110         "usage: %s [OPTS] interface-list\n"
0111         "\nOPTS:\n"
0112         "    -d    detach program\n"
0113         "    -S    use skb-mode\n"
0114         "    -F    force loading prog\n"
0115         "    -D    direct table lookups (skip fib rules)\n",
0116         prog);
0117 }
0118
0119 int main(int argc, char **argv)
0120 {
0121     const char *prog_name = "xdp_fwd";
0122     struct bpf_program *prog = NULL;
0123     struct bpf_program *pos;
0124     const char *sec_name;
0125     int prog_fd = -1, map_fd = -1;
0126     char filename[PATH_MAX];
0127     struct bpf_object *obj;
0128     int opt, i, idx, err;
0129     int attach = 1;
0130     int ret = 0;
0131
0132     while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
0133         switch (opt) {
0134         case 'd':
0135             attach = 0;
0136             break;
0137         case 'S':
0138             xdp_flags |= XDP_FLAGS_SKB_MODE;
0139             break;
0140         case 'F':
0141             xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
0142             break;
0143         case 'D':
0144             prog_name = "xdp_fwd_direct";
0145             break;
0146         default:
0147             usage(basename(argv[0]));
0148             return 1;
0149         }
0150     }
0151
0152     if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
0153         xdp_flags |= XDP_FLAGS_DRV_MODE;
0154
0155     if (optind == argc) {
0156         usage(basename(argv[0]));
0157         return 1;
0158     }
0159
0160     if (attach) {
0161         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
0162
0163         if (access(filename, O_RDONLY) < 0) {
0164             printf("error accessing file %s: %s\n",
0165                 filename, strerror(errno));
0166             return 1;
0167         }
0168
0169         obj = bpf_object__open_file(filename, NULL);
0170         if (libbpf_get_error(obj))
0171             return 1;
0172
0173         prog = bpf_object__next_program(obj, NULL);
0174         bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
0175
0176         err = bpf_object__load(obj);
0177         if (err) {
0178             printf("Does kernel support devmap lookup?\n");
0179             /* If not, the error message will be:
0180              *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
0181              */
0182             return 1;
0183         }
0184
0185         bpf_object__for_each_program(pos, obj) {
0186             sec_name = bpf_program__section_name(pos);
0187             if (sec_name && !strcmp(sec_name, prog_name)) {
0188                 prog = pos;
0189                 break;
0190             }
0191         }
0192         prog_fd = bpf_program__fd(prog);
0193         if (prog_fd < 0) {
0194             printf("program not found: %s\n", strerror(prog_fd));
0195             return 1;
0196         }
0197         map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
0198                             "xdp_tx_ports"));
0199         if (map_fd < 0) {
0200             printf("map not found: %s\n", strerror(map_fd));
0201             return 1;
0202         }
0203     }
0204
0205     for (i = optind; i < argc; ++i) {
0206         idx = if_nametoindex(argv[i]);
0207         if (!idx)
0208             idx = strtoul(argv[i], NULL, 0);
0209
0210         if (!idx) {
0211             fprintf(stderr, "Invalid arg\n");
0212             return 1;
0213         }
0214         if (!attach) {
0215             err = do_detach(idx, argv[i], prog_name);
0216             if (err)
0217                 ret = err;
0218         } else {
0219             err = do_attach(idx, prog_fd, map_fd, argv[i]);
0220             if (err)
0221                 ret = err;
0222         }
0223     }
0224
0225     return ret;
0226 }