samples: bpf: Refactor test_cgrp2_sock2 program with libbpf

This commit refactors the existing cgroup program with libbpf bpf
loader. The original test_cgrp2_sock2 has keeped the bpf program
attached to the cgroup hierarchy even after the exit of user program.
To implement the same functionality with libbpf, this commit uses the
BPF_LINK_PINNING to pin the link attachment even after it is closed.

Since this uses LINK instead of ATTACH, detach of bpf program from
cgroup with 'test_cgrp2_sock' is not used anymore.

The code to mount the bpf was added to the .sh file in case the bpff
was not mounted on /sys/fs/bpf. Additionally, to fix the problem that
shell script cannot find the binary object from the current path,
relative path './' has been added in front of binary.

Fixes: 554ae6e792ef3 ("samples/bpf: add userspace example for prohibiting sockets")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201124090310.24374-3-danieltimlee@gmail.com

1 files changed, 17 insertions, 4 deletions

diff --git a/samples/bpf/test_cgrp2_sock2.sh b/samples/bpf/test_cgrp2_sock2.sh
index 0f396a86e0cb..6a3dbe642b2b 100755
--- a/samples/bpf/test_cgrp2_sock2.sh
+++ b/samples/bpf/test_cgrp2_sock2.sh
@@ -1,6 +1,9 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+BPFFS=/sys/fs/bpf
+LINK_PIN=$BPFFS/test_cgrp2_sock2
+
 function config_device {
 	ip netns add at_ns0
 	ip link add veth0 type veth peer name veth0b
@@ -21,16 +24,22 @@ function config_cgroup {
 	echo $$ >> /tmp/cgroupv2/foo/cgroup.procs
 }
 
+function config_bpffs {
+	if mount | grep $BPFFS > /dev/null; then
+		echo "bpffs already mounted"
+	else
+		echo "bpffs not mounted. Mounting..."
+		mount -t bpf none $BPFFS
+	fi
+}
 
 function attach_bpf {
-	test_cgrp2_sock2 /tmp/cgroupv2/foo sock_flags_kern.o $1
+	./test_cgrp2_sock2 /tmp/cgroupv2/foo sock_flags_kern.o $1
 	[ $? -ne 0 ] && exit 1
 }
 
 function cleanup {
-	if [ -d /tmp/cgroupv2/foo ]; then
-		test_cgrp2_sock -d /tmp/cgroupv2/foo
-	fi
+	rm -rf $LINK_PIN
 	ip link del veth0b
 	ip netns delete at_ns0
 	umount /tmp/cgroupv2
@@ -42,6 +51,7 @@ cleanup 2>/dev/null
 set -e
 config_device
 config_cgroup
+config_bpffs
 set +e
 
 #
@@ -62,6 +72,9 @@ if [ $? -eq 0 ]; then
 	exit 1
 fi
 
+rm -rf $LINK_PIN
+sleep 1                 # Wait for link detach
+
 #
 # Test 2 - fail ping
 #