LXR linux/samples/bpf/load_sock

   1/* Copyright (c) 2017 Facebook
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 */
   7#include <stdio.h>
   8#include <stdlib.h>
   9#include <string.h>
  10#include <linux/bpf.h>
  11#include "libbpf.h"
  12#include "bpf_load.h"
  13#include <unistd.h>
  14#include <errno.h>
  15#include <fcntl.h>
  16#include <linux/unistd.h>
  17
  18static void usage(char *pname)
  19{
  20        printf("USAGE:\n  %s [-l] <cg-path> <prog filename>\n", pname);
  21        printf("\tLoad and attach a sock_ops program to the specified "
  22               "cgroup\n");
  23        printf("\tIf \"-l\" is used, the program will continue to run\n");
  24        printf("\tprinting the BPF log buffer\n");
  25        printf("\tIf the specified filename does not end in \".o\", it\n");
  26        printf("\tappends \"_kern.o\" to the name\n");
  27        printf("\n");
  28        printf("  %s -r <cg-path>\n", pname);
  29        printf("\tDetaches the currently attached sock_ops program\n");
  30        printf("\tfrom the specified cgroup\n");
  31        printf("\n");
  32        exit(1);
  33}
  34
  35int main(int argc, char **argv)
  36{
  37        int logFlag = 0;
  38        int error = 0;
  39        char *cg_path;
  40        char fn[500];
  41        char *prog;
  42        int cg_fd;
  43
  44        if (argc < 3)
  45                usage(argv[0]);
  46
  47        if (!strcmp(argv[1], "-r")) {
  48                cg_path = argv[2];
  49                cg_fd = open(cg_path, O_DIRECTORY, O_RDONLY);
  50                error = bpf_prog_detach(cg_fd, BPF_CGROUP_SOCK_OPS);
  51                if (error) {
  52                        printf("ERROR: bpf_prog_detach: %d (%s)\n",
  53                               error, strerror(errno));
  54                        return 2;
  55                }
  56                return 0;
  57        } else if (!strcmp(argv[1], "-h")) {
  58                usage(argv[0]);
  59        } else if (!strcmp(argv[1], "-l")) {
  60                logFlag = 1;
  61                if (argc < 4)
  62                        usage(argv[0]);
  63        }
  64
  65        prog = argv[argc - 1];
  66        cg_path = argv[argc - 2];
  67        if (strlen(prog) > 480) {
  68                fprintf(stderr, "ERROR: program name too long (> 480 chars)\n");
  69                return 3;
  70        }
  71        cg_fd = open(cg_path, O_DIRECTORY, O_RDONLY);
  72
  73        if (!strcmp(prog + strlen(prog)-2, ".o"))
  74                strcpy(fn, prog);
  75        else
  76                sprintf(fn, "%s_kern.o", prog);
  77        if (logFlag)
  78                printf("loading bpf file:%s\n", fn);
  79        if (load_bpf_file(fn)) {
  80                printf("ERROR: load_bpf_file failed for: %s\n", fn);
  81                printf("%s", bpf_log_buf);
  82                return 4;
  83        }
  84        if (logFlag)
  85                printf("TCP BPF Loaded %s\n", fn);
  86
  87        error = bpf_prog_attach(prog_fd[0], cg_fd, BPF_CGROUP_SOCK_OPS, 0);
  88        if (error) {
  89                printf("ERROR: bpf_prog_attach: %d (%s)\n",
  90                       error, strerror(errno));
  91                return 5;
  92        } else if (logFlag) {
  93                read_trace_pipe();
  94        }
  95
  96        return error;
  97}
  98