diff options
| -rw-r--r-- | kernel/bpf/syscall.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0afb4eaa1887..b513659d120f 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -357,6 +357,40 @@ void bpf_register_prog_type(struct bpf_prog_type_list *tl) list_add(&tl->list_node, &bpf_prog_types); } +/* fixup insn->imm field of bpf_call instructions: + * if (insn->imm == BPF_FUNC_map_lookup_elem) + * insn->imm = bpf_map_lookup_elem - __bpf_call_base; + * else if (insn->imm == BPF_FUNC_map_update_elem) + * insn->imm = bpf_map_update_elem - __bpf_call_base; + * else ... + * + * this function is called after eBPF program passed verification + */ +static void fixup_bpf_calls(struct bpf_prog *prog) +{ + const struct bpf_func_proto *fn; + int i; + + for (i = 0; i < prog->len; i++) { + struct bpf_insn *insn = &prog->insnsi[i]; + + if (insn->code == (BPF_JMP | BPF_CALL)) { + /* we reach here when program has bpf_call instructions + * and it passed bpf_check(), means that + * ops->get_func_proto must have been supplied, check it + */ + BUG_ON(!prog->aux->ops->get_func_proto); + + fn = prog->aux->ops->get_func_proto(insn->imm); + /* all functions that have prototype and verifier allowed + * programs to call them, must be real in-kernel functions + */ + BUG_ON(!fn->func); + insn->imm = fn->func - __bpf_call_base; + } + } +} + /* drop refcnt on maps used by eBPF program and free auxilary data */ static void free_used_maps(struct bpf_prog_aux *aux) { @@ -478,6 +512,9 @@ static int bpf_prog_load(union bpf_attr *attr) if (err < 0) goto free_used_maps; + /* fixup BPF_CALL->imm field */ + fixup_bpf_calls(prog); + /* eBPF program is ready to be JITed */ bpf_prog_select_runtime(prog); |