selftests/bpf: Add bpf_icmp_send kfunc cgroup_skb tests

Browse source

This test opens a server and client, enters a new cgroup, attach a
cgroup_skb program on egress and calls the bpf_icmp_send function from
the client egress so that an ICMP unreach control message is sent back
to the client. It then fetches the message from the error queue to
confirm the correct ICMP unreach code has been sent.

Note that, for the client, we have to connect in non-blocking mode to
let the test execute faster. Otherwise, we need to wait for the TCP
three-way handshake to timeout in the kernel before reading the errno.

Also note that we don't set IP_RECVERR on the socket in
connect_to_fd_nonblock since the error will be transferred anyway in our
test because the connection is rejected at the beginning of the TCP
handshake. See in net/ipv4/tcp_ipv4.c:tcp_v4_err for more details.

Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jordan Rife <jordan@jrife.io>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/bpf/20260709144900.245904-3-mahe.tardy@gmail.com

...

This commit is contained in:

Mahe Tardy 2026-07-09 14:48:57 +00:00 • committed by Daniel Borkmann

parent f3603df9ae

commit 39b337a3d9

2 changed files with 202 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

164

tools/testing/selftests/bpf/prog_tests/icmp_send_kfunc.c

View file

38

tools/testing/selftests/bpf/progs/icmp_send.c

View file