+static inline int sk_skb_try_make_writable(struct sk_buff *skb,
+ unsigned int write_len)
+{
+ int err = __bpf_try_make_writable(skb, write_len);
+
+ bpf_compute_data_end_sk_skb(skb);
+ return err;
+}
+
+BPF_CALL_2(sk_skb_pull_data, struct sk_buff *, skb, u32, len)
+{
+ /* Idea is the following: should the needed direct read/write
+ * test fail during runtime, we can pull in more data and redo
+ * again, since implicitly, we invalidate previous checks here.
+ *
+ * Or, since we know how much we need to make read/writeable,
+ * this can be done once at the program beginning for direct
+ * access case. By this we overcome limitations of only current
+ * headroom being accessible.
+ */
+ return sk_skb_try_make_writable(skb, len ? : skb_headlen(skb));
+}
+
+static const struct bpf_func_proto sk_skb_pull_data_proto = {
+ .func = sk_skb_pull_data,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+