samples/bpf/load_sock_ops.c

   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
  18 static 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
  35 int 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 }