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Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/syscall.c37
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);