bpf: add helper to invalidate hash
Add a small helper that complements 36bbef52c7eb ("bpf: direct packet
write and access for helpers for clsact progs") for invalidating the
current skb->hash after mangling on headers via direct packet write.
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 e07432b..f09c70b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -419,6 +419,13 @@
*/
BPF_FUNC_csum_update,
+ /**
+ * bpf_set_hash_invalid(skb)
+ * Invalidate current skb>hash.
+ * @skb: pointer to skb
+ */
+ BPF_FUNC_set_hash_invalid,
+
__BPF_FUNC_MAX_ID,
};
diff --git a/net/core/filter.c b/net/core/filter.c
index acf84fb..00351cd 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1777,6 +1777,22 @@
.arg1_type = ARG_PTR_TO_CTX,
};
+BPF_CALL_1(bpf_set_hash_invalid, struct sk_buff *, skb)
+{
+ /* After all direct packet write, this can be used once for
+ * triggering a lazy recalc on next skb_get_hash() invocation.
+ */
+ skb_clear_hash(skb);
+ return 0;
+}
+
+static const struct bpf_func_proto bpf_set_hash_invalid_proto = {
+ .func = bpf_set_hash_invalid,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
BPF_CALL_3(bpf_skb_vlan_push, struct sk_buff *, skb, __be16, vlan_proto,
u16, vlan_tci)
{
@@ -2534,6 +2550,8 @@
return &bpf_get_route_realm_proto;
case BPF_FUNC_get_hash_recalc:
return &bpf_get_hash_recalc_proto;
+ case BPF_FUNC_set_hash_invalid:
+ return &bpf_set_hash_invalid_proto;
case BPF_FUNC_perf_event_output:
return &bpf_skb_event_output_proto;
case BPF_FUNC_get_smp_processor_id: