kernel/bpf/bpf_lsm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Copyright (C) 2020 Google LLC.
   5  */
   6
   7 #include <linux/filter.h>
   8 #include <linux/bpf.h>
   9 #include <linux/btf.h>
  10 #include <linux/lsm_hooks.h>
  11 #include <linux/bpf_lsm.h>
  12 #include <linux/kallsyms.h>
  13 #include <linux/bpf_verifier.h>
  14 #include <net/bpf_sk_storage.h>
  15 #include <linux/bpf_local_storage.h>
  16 #include <linux/btf_ids.h>
  17
  18 /* For every LSM hook that allows attachment of BPF programs, declare a nop
  19  * function where a BPF program can be attached.
  20  */
  21 #define LSM_HOOK(RET, DEFAULT, NAME, ...)       \
  22 noinline RET bpf_lsm_##NAME(__VA_ARGS__)        \
  23 {                                               \
  24         return DEFAULT;                         \
  25 }
  26
  27 #include <linux/lsm_hook_defs.h>
  28 #undef LSM_HOOK
  29
  30 #define LSM_HOOK(RET, DEFAULT, NAME, ...) BTF_ID(func, bpf_lsm_##NAME)
  31 BTF_SET_START(bpf_lsm_hooks)
  32 #include <linux/lsm_hook_defs.h>
  33 #undef LSM_HOOK
  34 BTF_SET_END(bpf_lsm_hooks)
  35
  36 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
  37                         const struct bpf_prog *prog)
  38 {
  39         if (!prog->gpl_compatible) {
  40                 bpf_log(vlog,
  41                         "LSM programs must have a GPL compatible license\n");
  42                 return -EINVAL;
  43         }
  44
  45         if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) {
  46                 bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
  47                         prog->aux->attach_btf_id, prog->aux->attach_func_name);
  48                 return -EINVAL;
  49         }
  50
  51         return 0;
  52 }
  53
  54 static const struct bpf_func_proto *
  55 bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
  56 {
  57         switch (func_id) {
  58         case BPF_FUNC_inode_storage_get:
  59                 return &bpf_inode_storage_get_proto;
  60         case BPF_FUNC_inode_storage_delete:
  61                 return &bpf_inode_storage_delete_proto;
  62         case BPF_FUNC_sk_storage_get:
  63                 return &bpf_sk_storage_get_proto;
  64         case BPF_FUNC_sk_storage_delete:
  65                 return &bpf_sk_storage_delete_proto;
  66         default:
  67                 return tracing_prog_func_proto(func_id, prog);
  68         }
  69 }
  70
  71 const struct bpf_prog_ops lsm_prog_ops = {
  72 };
  73
  74 const struct bpf_verifier_ops lsm_verifier_ops = {
  75         .get_func_proto = bpf_lsm_func_proto,
  76         .is_valid_access = btf_ctx_access,
  77 };