linux/samples/bpf/sock_example.c, branch v3.19Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
https://git.shady.money/linux/atom?h=v3.192014-12-06T05:47:32Zsamples: bpf: example of stateful socket filtering2014-12-06T05:47:32ZAlexei Starovoitovast@plumgrid.com2014-12-01T23:06:36Zurn:sha1:03f4723ed7a52bd31da26eefe2cdde563ea0f468
this socket filter example does:
- creates arraymap in kernel with key 4 bytes and value 8 bytes
- loads eBPF program which assumes that packet is IPv4 and loads one byte of
IP->proto from the packet and uses it as a key in a map
r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)];
*(u32*)(fp - 4) = r0;
value = bpf_map_lookup_elem(map_fd, fp - 4);
if (value)
(*(u64*)value) += 1;
- attaches this program to raw socket
- every second user space reads map[IPPROTO_TCP], map[IPPROTO_UDP], map[IPPROTO_ICMP]
to see how many packets of given protocol were seen on loopback interface
Usage:
$sudo samples/bpf/sock_example
TCP 0 UDP 0 ICMP 0 packets
TCP 187600 UDP 0 ICMP 4 packets
TCP 376504 UDP 0 ICMP 8 packets
TCP 563116 UDP 0 ICMP 12 packets
TCP 753144 UDP 0 ICMP 16 packets
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>