Add selftests for bpf_skb_ancestor_cgroup_id helper.

test_skb_cgroup_id.sh prepares testing interface and adds tc qdisc and
filter for it using BPF object compiled from test_skb_cgroup_id_kern.c
program.

BPF program in test_skb_cgroup_id_kern.c gets ancestor cgroup id using
the new helper at different levels of cgroup hierarchy that skb belongs
to, including root level and non-existing level, and saves it to the map
where the key is the level of corresponding cgroup and the value is its
id.

To trigger BPF program, user space program test_skb_cgroup_id_user is
run. It adds itself into testing cgroup and sends UDP datagram to
link-local multicast address of testing interface. Then it reads cgroup
ids saved in kernel for different levels from the BPF map and compares
them with those in user space. They must be equal for every level of
ancestry.

Example of run:
  # ./test_skb_cgroup_id.sh
  Wait for testing link-local IP to become available ... OK
  Note: 8 bytes struct bpf_elf_map fixup performed due to size mismatch!
  [PASS]

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch add tests for the new BPF_PROG_TYPE_SK_REUSEPORT.

The tests cover:
- IPv4/IPv6 + TCP/UDP
- TCP syncookie
- TCP fastopen
- Cases when the bpf_sk_select_reuseport() returning errors
- Cases when the bpf prog returns SK_DROP
- Values from sk_reuseport_md
- outer_map => reuseport_array

The test depends on
commit 3eee1f75f2b9 ("bpf: fix bpf_skb_load_bytes_relative pkt length check")

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Daniel Borkmann says:

====================
pull-request: bpf-next 2018-08-07

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Add cgroup local storage for BPF programs, which provides a fast
   accessible memory for storing various per-cgroup data like number
   of transmitted packets, etc, from Roman.

2) Support bpf_get_socket_cookie() BPF helper in several more program
   types that have a full socket available, from Andrey.

3) Significantly improve the performance of perf events which are
   reported from BPF offload. Also convert a couple of BPF AF_XDP
   samples overto use libbpf, both from Jakub.

4) seg6local LWT provides the End.DT6 action, which allows to
   decapsulate an outer IPv6 header containing a Segment Routing Header.
   Adds this action now to the seg6local BPF interface, from Mathieu.

5) Do not mark dst register as unbounded in MOV64 instruction when
   both src and dst register are the same, from Arthur.

6) Define u_smp_rmb() and u_smp_wmb() to their respective barrier
   instructions on arm64 for the AF_XDP sample code, from Brian.

7) Convert the tcp_client.py and tcp_server.py BPF selftest scripts
   over from Python 2 to Python 3, from Jeremy.

8) Enable BTF build flags to the BPF sample code Makefile, from Taeung.

9) Remove an unnecessary rcu_read_lock() in run_lwt_bpf(), from Taehee.

10) Several improvements to the README.rst from the BPF documentation
    to make it more consistent with RST format, from Tobin.

11) Replace all occurrences of strerror() by calls to strerror_r()
    in libbpf and fix a FORTIFY_SOURCE build error along with it,
    from Thomas.

12) Fix a bug in bpftool's get_btf() function to correctly propagate
    an error via PTR_ERR(), from Yue.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Implement a test to cover the cgroup storage functionality.
The test implements a bpf program which drops every second packet
by using the cgroup storage as a persistent storage.

The test also use the userspace API to check the data
in the cgroup storage, alter it, and check that the loaded
and attached bpf program sees the update.

Expected output:
  $ ./test_cgroup_storage
  test_cgroup_storage:PASS

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add test to use get_socket_cookie() from BPF programs of types
BPF_PROG_TYPE_SOCK_OPS and BPF_PROG_TYPE_CGROUP_SOCK_ADDR.

The test attaches two programs to cgroup, runs TCP server and client in
the cgroup and checks that two operations are done properly on client
socket when user calls connect(2):

1. In BPF_CGROUP_INET6_CONNECT socket cookie is used as the key to write
   new value in a map for client socket.

2. In BPF_CGROUP_SOCK_OPS (BPF_SOCK_OPS_TCP_CONNECT_CB callback) the
   value written in "1." is found by socket cookie, since it's the same
   socket, and updated.

Finally the test verifies the value in the map.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

I noticed the "--version" option of the llvm-objcopy command has recently
disappeared from the master llvm branch.  It is currently used as a BTF
support test in tools/testing/selftests/bpf/Makefile.

This patch replaces it with "--help" which should be
less error prone in the future.

Fixes: c0fa1b6c3efc ("bpf: btf: Add BTF tests")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Switch to cgroup_helpers to simplify the code and fix cgroup cleanup:
before cgroup was not cleaned up after the test.

It also removes SYSTEM macro, that only printed error, but didn't
terminate the test.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

gcc complains that urandom_read gets built twice.

gcc -o tools/testing/selftests/bpf/urandom_read
-static urandom_read.c -Wl,--build-id
gcc -Wall -O2 -I../../../include/uapi -I../../../lib -I../../../lib/bpf
-I../../../../include/generated  -I../../../include    urandom_read.c
urandom_read -lcap -lelf -lrt -lpthread -o
tools/testing/selftests/bpf/urandom_read
gcc: fatal error: input file
‘tools/testing/selftests/bpf/urandom_read’ is the
same as output file
compilation terminated.
../lib.mk:110: recipe for target
'tools/testing/selftests/bpf/urandom_read' failed
To fix this issue remove the urandom_read target and so target
TEST_CUSTOM_PROGS gets used.

Fixes: 81f77fd0deeb ("bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Syscall name_to_handle_at() can be used to get cgroup id
for a particular cgroup path in user space. The selftest
got cgroup id from both user and kernel, and compare to
ensure they are equal to each other.

Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>