1 // SPDX-License-Identifier: GPL-2.0 2 /* eBPF example program: 3 * 4 * - Loads eBPF program 5 * 6 * The eBPF program loads a filter from file and attaches the 7 * program to a cgroup using BPF_PROG_ATTACH 8 */ 9 10 #define _GNU_SOURCE 11 12 #include <stdio.h> 13 #include <stdlib.h> 14 #include <stddef.h> 15 #include <string.h> 16 #include <unistd.h> 17 #include <assert.h> 18 #include <errno.h> 19 #include <fcntl.h> 20 #include <net/if.h> 21 #include <linux/bpf.h> 22 #include <bpf/bpf.h> 23 #include <bpf/libbpf.h> 24 25 #include "bpf_insn.h" 26 27 static int usage(const char *argv0) 28 { 29 printf("Usage: %s cg-path filter-path [filter-id]\n", argv0); 30 return EXIT_FAILURE; 31 } 32 33 int main(int argc, char **argv) 34 { 35 int cg_fd, err, ret = EXIT_FAILURE, filter_id = 0, prog_cnt = 0; 36 const char *link_pin_path = "/sys/fs/bpf/test_cgrp2_sock2"; 37 struct bpf_link *link = NULL; 38 struct bpf_program *progs[2]; 39 struct bpf_program *prog; 40 struct bpf_object *obj; 41 42 if (argc < 3) 43 return usage(argv[0]); 44 45 if (argc > 3) 46 filter_id = atoi(argv[3]); 47 48 cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY); 49 if (cg_fd < 0) { 50 printf("Failed to open cgroup path: '%s'\n", strerror(errno)); 51 return ret; 52 } 53 54 obj = bpf_object__open_file(argv[2], NULL); 55 if (libbpf_get_error(obj)) { 56 printf("ERROR: opening BPF object file failed\n"); 57 return ret; 58 } 59 60 bpf_object__for_each_program(prog, obj) { 61 progs[prog_cnt] = prog; 62 prog_cnt++; 63 } 64 65 if (filter_id >= prog_cnt) { 66 printf("Invalid program id; program not found in file\n"); 67 goto cleanup; 68 } 69 70 /* load BPF program */ 71 if (bpf_object__load(obj)) { 72 printf("ERROR: loading BPF object file failed\n"); 73 goto cleanup; 74 } 75 76 link = bpf_program__attach_cgroup(progs[filter_id], cg_fd); 77 if (libbpf_get_error(link)) { 78 printf("ERROR: bpf_program__attach failed\n"); 79 link = NULL; 80 goto cleanup; 81 } 82 83 err = bpf_link__pin(link, link_pin_path); 84 if (err < 0) { 85 printf("ERROR: bpf_link__pin failed: %d\n", err); 86 goto cleanup; 87 } 88 89 ret = EXIT_SUCCESS; 90 91 cleanup: 92 bpf_link__destroy(link); 93 bpf_object__close(obj); 94 return ret; 95 } 96