bpf: add bpf_get_hash_recalc helper
If skb_clear_hash() was invoked due to mangling of relevant headers and
BPF program needs skb->hash later on, we can add a helper to trigger hash
recalculation via bpf_get_hash_recalc().
The helper will return the newly retrieved hash directly, but later access
can also be done via skb context again through skb->hash directly (inline)
without needing to call the helper once more.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f44504d..c14ca1c 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -348,6 +348,15 @@
* < 0 error
*/
BPF_FUNC_skb_in_cgroup,
+
+ /**
+ * bpf_get_hash_recalc(skb)
+ * Retrieve and possibly recalculate skb->hash.
+ * @skb: pointer to skb
+ * Return: hash
+ */
+ BPF_FUNC_get_hash_recalc,
+
__BPF_FUNC_MAX_ID,
};