src/basic/bpf-program.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2016 Daniel Mack
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <fcntl.h>
  21 #include <sys/stat.h>
  22 #include <sys/types.h>
  23 #include <unistd.h>
  24
  25 #include "alloc-util.h"
  26 #include "bpf-program.h"
  27 #include "fd-util.h"
  28 #include "log.h"
  29 #include "missing.h"
  30
  31 int bpf_program_new(uint32_t prog_type, BPFProgram **ret) {
  32         _cleanup_(bpf_program_unrefp) BPFProgram *p = NULL;
  33
  34         p = new0(BPFProgram, 1);
  35         if (!p)
  36                 return log_oom();
  37
  38         p->prog_type = prog_type;
  39         p->kernel_fd = -1;
  40
  41         *ret = p;
  42         p = NULL;
  43         return 0;
  44 }
  45
  46 BPFProgram *bpf_program_unref(BPFProgram *p) {
  47         if (!p)
  48                 return NULL;
  49
  50         safe_close(p->kernel_fd);
  51         free(p->instructions);
  52
  53         return mfree(p);
  54 }
  55
  56 int bpf_program_add_instructions(BPFProgram *p, const struct bpf_insn *instructions, size_t count) {
  57
  58         assert(p);
  59
  60         if (!GREEDY_REALLOC(p->instructions, p->allocated, p->n_instructions + count))
  61                 return -ENOMEM;
  62
  63         memcpy(p->instructions + p->n_instructions, instructions, sizeof(struct bpf_insn) * count);
  64         p->n_instructions += count;
  65
  66         return 0;
  67 }
  68
  69 int bpf_program_load_kernel(BPFProgram *p, char *log_buf, size_t log_size) {
  70         union bpf_attr attr;
  71
  72         assert(p);
  73
  74         if (p->kernel_fd >= 0)
  75                 return -EBUSY;
  76
  77         attr = (union bpf_attr) {
  78                 .prog_type = p->prog_type,
  79                 .insns = PTR_TO_UINT64(p->instructions),
  80                 .insn_cnt = p->n_instructions,
  81                 .license = PTR_TO_UINT64("GPL"),
  82                 .log_buf = PTR_TO_UINT64(log_buf),
  83                 .log_level = !!log_buf,
  84                 .log_size = log_size,
  85         };
  86
  87         p->kernel_fd = bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  88         if (p->kernel_fd < 0)
  89                 return -errno;
  90
  91         return 0;
  92 }
  93
  94 int bpf_program_cgroup_attach(BPFProgram *p, int type, const char *path, uint32_t flags) {
  95         _cleanup_close_ int fd = -1;
  96         union bpf_attr attr;
  97
  98         assert(p);
  99         assert(type >= 0);
 100         assert(path);
 101
 102         fd = open(path, O_DIRECTORY|O_RDONLY|O_CLOEXEC);
 103         if (fd < 0)
 104                 return -errno;
 105
 106         attr = (union bpf_attr) {
 107                 .attach_type = type,
 108                 .target_fd = fd,
 109                 .attach_bpf_fd = p->kernel_fd,
 110                 .attach_flags = flags,
 111         };
 112
 113         if (bpf(BPF_PROG_ATTACH, &attr, sizeof(attr)) < 0)
 114                 return -errno;
 115
 116         return 0;
 117 }
 118
 119 int bpf_program_cgroup_detach(int type, const char *path) {
 120         _cleanup_close_ int fd = -1;
 121         union bpf_attr attr;
 122
 123         assert(path);
 124
 125         fd = open(path, O_DIRECTORY|O_RDONLY|O_CLOEXEC);
 126         if (fd < 0)
 127                 return -errno;
 128
 129         attr = (union bpf_attr) {
 130                 .attach_type = type,
 131                 .target_fd = fd,
 132         };
 133
 134         if (bpf(BPF_PROG_DETACH, &attr, sizeof(attr)) < 0)
 135                 return -errno;
 136
 137         return 0;
 138 }
 139
 140 int bpf_map_new(enum bpf_map_type type, size_t key_size, size_t value_size, size_t max_entries, uint32_t flags) {
 141         union bpf_attr attr = {
 142                 .map_type = type,
 143                 .key_size = key_size,
 144                 .value_size = value_size,
 145                 .max_entries = max_entries,
 146                 .map_flags = flags,
 147         };
 148         int fd;
 149
 150         fd = bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
 151         if (fd < 0)
 152                 return -errno;
 153
 154         return fd;
 155 }
 156
 157 int bpf_map_update_element(int fd, const void *key, void *value) {
 158
 159         union bpf_attr attr = {
 160                 .map_fd = fd,
 161                 .key = PTR_TO_UINT64(key),
 162                 .value = PTR_TO_UINT64(value),
 163         };
 164
 165         if (bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr)) < 0)
 166                 return -errno;
 167
 168         return 0;
 169 }
 170
 171 int bpf_map_lookup_element(int fd, const void *key, void *value) {
 172
 173         union bpf_attr attr = {
 174                 .map_fd = fd,
 175                 .key = PTR_TO_UINT64(key),
 176                 .value = PTR_TO_UINT64(value),
 177         };
 178
 179         if (bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr)) < 0)
 180                 return -errno;
 181
 182         return 0;
 183 }