packet: add classic BPF fanout mode
Add fanout mode PACKET_FANOUT_CBPF that accepts a classic BPF program
to select a socket.
This avoids having to keep adding special case fanout modes. One
example use case is application layer load balancing. The QUIC
protocol, for instance, encodes a connection ID in UDP payload.
Also add socket option SOL_PACKET/PACKET_FANOUT_DATA that updates data
associated with the socket group. Fanout mode PACKET_FANOUT_CBPF is the
only user so far.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/internal.h b/net/packet/internal.h
index e20b3e8..9ee4631 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -79,7 +79,10 @@
u16 id;
u8 type;
u8 flags;
- atomic_t rr_cur;
+ union {
+ atomic_t rr_cur;
+ struct bpf_prog __rcu *bpf_prog;
+ };
struct list_head list;
struct sock *arr[PACKET_FANOUT_MAX];
spinlock_t lock;