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@xxxxxxxxx>
---
Changes in v2:
- change to destroy link even after link__pin()
- enhance error message
samples/bpf/Makefile | 2 +-
samples/bpf/test_cgrp2_sock2.c | 61 ++++++++++++++++++++++++---------
samples/bpf/test_cgrp2_sock2.sh | 21 +++++++++---
3 files changed, 62 insertions(+), 22 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 7c61118525f7..d31e082c369e 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -82,7 +82,7 @@ test_overhead-objs := bpf_load.o test_overhead_user.o
test_cgrp2_array_pin-objs := test_cgrp2_array_pin.o
test_cgrp2_attach-objs := test_cgrp2_attach.o
test_cgrp2_sock-objs := test_cgrp2_sock.o
-test_cgrp2_sock2-objs := bpf_load.o test_cgrp2_sock2.o
+test_cgrp2_sock2-objs := test_cgrp2_sock2.o
xdp1-objs := xdp1_user.o
# reuse xdp1 source intentionally
xdp2-objs := xdp1_user.o
diff --git a/samples/bpf/test_cgrp2_sock2.c b/samples/bpf/test_cgrp2_sock2.c
index a9277b118c33..e7060aaa2f5a 100644
--- a/samples/bpf/test_cgrp2_sock2.c
+++ b/samples/bpf/test_cgrp2_sock2.c
@@ -20,9 +20,9 @@
#include <net/if.h>
#include <linux/bpf.h>
#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
#include "bpf_insn.h"
-#include "bpf_load.h"
static int usage(const char *argv0)
{
@@ -32,37 +32,64 @@ static int usage(const char *argv0)
int main(int argc, char **argv)
{
- int cg_fd, ret, filter_id = 0;
+ int cg_fd, err, ret = EXIT_FAILURE, filter_id = 0, prog_cnt = 0;
+ const char *link_pin_path = "/sys/fs/bpf/test_cgrp2_sock2";
+ struct bpf_link *link = NULL;
+ struct bpf_program *progs[2];
+ struct bpf_program *prog;
+ struct bpf_object *obj;
if (argc < 3)
return usage(argv[0]);
+ if (argc > 3)
+ filter_id = atoi(argv[3]);
+
cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
if (cg_fd < 0) {
printf("Failed to open cgroup path: '%s'\n", strerror(errno));
- return EXIT_FAILURE;
+ return ret;
}
- if (load_bpf_file(argv[2]))
- return EXIT_FAILURE;
-
- printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
+ obj = bpf_object__open_file(argv[2], NULL);
+ if (libbpf_get_error(obj)) {
+ printf("ERROR: opening BPF object file failed\n");
+ return ret;
+ }
- if (argc > 3)
- filter_id = atoi(argv[3]);
+ bpf_object__for_each_program(prog, obj) {
+ progs[prog_cnt] = prog;
+ prog_cnt++;
+ }
if (filter_id >= prog_cnt) {
printf("Invalid program id; program not found in file\n");
- return EXIT_FAILURE;
+ goto cleanup;
+ }
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ printf("ERROR: loading BPF object file failed\n");
+ goto cleanup;
}
- ret = bpf_prog_attach(prog_fd[filter_id], cg_fd,
- BPF_CGROUP_INET_SOCK_CREATE, 0);
- if (ret < 0) {
- printf("Failed to attach prog to cgroup: '%s'\n",
- strerror(errno));
- return EXIT_FAILURE;
+ link = bpf_program__attach_cgroup(progs[filter_id], cg_fd);
+ if (libbpf_get_error(link)) {
+ printf("ERROR: bpf_program__attach failed\n");
+ link = NULL;
+ goto cleanup;
}
- return EXIT_SUCCESS;
+ err = bpf_link__pin(link, link_pin_path);
+ if (err < 0) {
+ printf("ERROR: bpf_link__pin failed: %d\n", err);
+ goto cleanup;
+ }
+
+ ret = EXIT_SUCCESS;
+
+cleanup:
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
+ return ret;
}
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
#
--
2.25.1
