src/shared/bpf-dlopen.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "alloc-util.h"
   4 #include "dlfcn-util.h"
   5 #include "bpf-dlopen.h"
   6
   7 #if HAVE_LIBBPF
   8 static void *bpf_dl = NULL;
   9
  10 struct bpf_link* (*sym_bpf_program__attach_cgroup)(struct bpf_program *, int);
  11 long (*sym_libbpf_get_error)(const void *);
  12 int (*sym_bpf_link__fd)(const struct bpf_link *);
  13 int (*sym_bpf_link__destroy)(struct bpf_link *);
  14 int (*sym_bpf_map__fd)(const struct bpf_map *);
  15 const char* (*sym_bpf_map__name)(const struct bpf_map *);
  16 int (*sym_bpf_map__resize)(struct bpf_map *, __u32);
  17 int (*sym_bpf_map_update_elem)(int, const void *, const void *, __u64);
  18 int (*sym_bpf_object__open_skeleton)(struct bpf_object_skeleton *, const struct bpf_object_open_opts *);
  19 int (*sym_bpf_object__load_skeleton)(struct bpf_object_skeleton *);
  20 int (*sym_bpf_object__attach_skeleton)(struct bpf_object_skeleton *);
  21 void (*sym_bpf_object__detach_skeleton)(struct bpf_object_skeleton *);
  22 void (*sym_bpf_object__destroy_skeleton)(struct bpf_object_skeleton *);
  23 bool (*sym_bpf_probe_prog_type)(enum bpf_prog_type, __u32);
  24 const char* (*sym_bpf_program__name)(const struct bpf_program *);
  25
  26 int dlopen_bpf(void) {
  27         _cleanup_(dlclosep) void *dl = NULL;
  28         int r;
  29
  30         if (bpf_dl)
  31                 return 0; /* Already loaded */
  32
  33         dl = dlopen("libbpf.so.0", RTLD_LAZY);
  34         if (!dl)
  35                 return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
  36                                        "libbpf is not installed: %s", dlerror());
  37
  38         r = dlsym_many_and_warn(
  39                         dl,
  40                         LOG_DEBUG,
  41                         DLSYM_ARG(bpf_link__destroy),
  42                         DLSYM_ARG(bpf_link__fd),
  43                         DLSYM_ARG(bpf_map__fd),
  44                         DLSYM_ARG(bpf_map__name),
  45                         DLSYM_ARG(bpf_map__resize),
  46                         DLSYM_ARG(bpf_map_update_elem),
  47                         DLSYM_ARG(bpf_object__open_skeleton),
  48                         DLSYM_ARG(bpf_object__load_skeleton),
  49                         DLSYM_ARG(bpf_object__attach_skeleton),
  50                         DLSYM_ARG(bpf_object__detach_skeleton),
  51                         DLSYM_ARG(bpf_object__destroy_skeleton),
  52                         DLSYM_ARG(bpf_probe_prog_type),
  53                         DLSYM_ARG(bpf_program__attach_cgroup),
  54                         DLSYM_ARG(bpf_program__name),
  55                         DLSYM_ARG(libbpf_get_error),
  56                         NULL);
  57         if (r < 0)
  58                 return r;
  59
  60         /* Note that we never release the reference here, because there's no real reason to, after all this
  61          * was traditionally a regular shared library dependency which lives forever too. */
  62         bpf_dl = TAKE_PTR(dl);
  63         return 1;
  64 }
  65
  66 #else
  67
  68 int dlopen_bpf(void) {
  69         return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
  70                                "libbpf support is not compiled in.");
  71 }
  72 #endif