tree 5e681c3d975fb0fe24d039b4ad4a24fbe330c393
parent 9290d742365a559adb79b0e3c00e88fa82d858ab
author Daniel Mack <daniel@zonque.org> 1479916350 +0100
committer Chenbo Feng <fengc@google.com> 1495492258 -0700

UPSTREAM: samples: bpf: add userspace example for attaching eBPF programs to cgroups

Cherry-pick from commit d8c5b17f2bc0de09fbbfa14d90e8168163a579e7

Add a simple userpace program to demonstrate the new API to attach eBPF
programs to cgroups. This is what it does:

 * Create arraymap in kernel with 4 byte keys and 8 byte values

 * Load eBPF program

   The eBPF program accesses the map passed in to store two pieces of
   information. The number of invocations of the program, which maps
   to the number of packets received, is stored to key 0. Key 1 is
   incremented on each iteration by the number of bytes stored in
   the skb.

 * Detach any eBPF program previously attached to the cgroup

 * Attach the new program to the cgroup using BPF_PROG_ATTACH

 * Once a second, read map[0] and map[1] to see how many bytes and
   packets were seen on any socket of tasks in the given cgroup.

The program takes a cgroup path as 1st argument, and either "ingress"
or "egress" as 2nd. Optionally, "drop" can be passed as 3rd argument,
which will make the generated eBPF program return 0 instead of 1, so
the kernel will drop the packet.

libbpf gained two new wrappers for the new syscall commands.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Bug: 30950746
Change-Id: I011436a755abd62050edd22e47995c166a0bd8a2