samples: bpf: example of stateful socket filtering
this socket filter example does:
- creates a hashtable in kernel with key 4 bytes and value 8 bytes
- populates map[6] = 0; map[17] = 0; // 6 - tcp_proto, 17 - udp_proto
- loads eBPF program:
r0 = skb[14 + 9]; // load one byte of ip->proto
*(u32*)(fp - 4) = r0;
value = bpf_map_lookup_elem(map_fd, fp - 4);
if (value)
(*(u64*)value) += 1;
- attaches this program to eth0 raw socket
- every second user space reads map[6] and map[17] to see how many
TCP and UDP packets were seen on eth0
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
3 files changed
