Re: Re: [PATCH bpf-next v4 2/2] selftests/bpf: Add testcase for bpf_task_under_cgroup
From: Feng Zhou
Date: Wed May 03 2023 - 23:24:24 EST
在 2023/4/29 00:32, Yonghong Song 写道:
On 4/28/23 12:17 AM, Feng zhou wrote:
From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
test_progs:
Tests new kfunc bpf_task_under_cgroup().
The bpf program saves the new task's pid within a given cgroup to
the remote_pid, which is convenient for the user-mode program to
verify the test correctness.
The user-mode program creates its own mount namespace, and mounts the
cgroupsv2 hierarchy in there, call the fork syscall, then check if
remote_pid and local_pid are unequal.
Signed-off-by: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
Ack with a few nits below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
.../bpf/prog_tests/task_under_cgroup.c | 55 +++++++++++++++++++
.../bpf/progs/test_task_under_cgroup.c | 51 +++++++++++++++++
3 files changed, 107 insertions(+)
create mode 100644
tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
create mode 100644
tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x
b/tools/testing/selftests/bpf/DENYLIST.s390x
index c7463f3ec3c0..5061d9e24c16 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -26,3 +26,4 @@ user_ringbuf # failed to
find kernel BTF type ID of
verif_stats #
trace_vprintk__open_and_load unexpected error:
-9 (?)
xdp_bonding # failed to auto-attach
program 'trace_on_entry': -524 (trampoline)
xdp_metadata # JIT does not support
calling kernel function (kfunc)
+test_task_under_cgroup # JIT does not support
calling kernel function (kfunc)
diff --git
a/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
new file mode 100644
index 000000000000..5e79dff86dec
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Bytedance */
+
+#include <sys/syscall.h>
+#include <test_progs.h>
+#include <cgroup_helpers.h>
+#include "test_task_under_cgroup.skel.h"
+
+#define FOO "/foo"
+
+void test_task_under_cgroup(void)
+{
+ struct test_task_under_cgroup *skel;
+ int ret, foo = -1;
+ pid_t pid;
+
+ foo = test__join_cgroup(FOO);
+ if (!ASSERT_OK(foo < 0, "cgroup_join_foo"))
+ return;
+
+ skel = test_task_under_cgroup__open();
+ if (!ASSERT_OK_PTR(skel, "test_task_under_cgroup__open"))
+ goto cleanup;
+
+ skel->rodata->local_pid = getpid();
+ skel->bss->remote_pid = getpid();
+ skel->rodata->cgid = get_cgroup_id(FOO);
+
+ ret = test_task_under_cgroup__load(skel);
+ if (!ASSERT_OK(ret, "test_task_under_cgroup__load"))
+ goto cleanup;
+
+ ret = test_task_under_cgroup__attach(skel);
+ if (!ASSERT_OK(ret, "test_task_under_cgroup__attach"))
+ goto cleanup;
+
+ pid = fork();
+ if (pid == 0)
+ exit(0);
+ else if (pid == -1)
+ printf("Couldn't fork process!\n");
ASSERT_* is preferred compared to 'printf'. Maybe ASSERT_TRUE(0,
"Couldn't fork process")?
Will do.
+
+ wait(NULL);
+
+ test_task_under_cgroup__detach(skel);
+
+ ASSERT_NEQ(skel->bss->remote_pid, skel->rodata->local_pid,
+ "test task_under_cgroup");
+
+cleanup:
+ if (foo >= 0)
"if (foo >= 0)" is not needed. 'foo' is guaranteed ">= 0" as this point.
Yes
+ close(foo);
+
+ test_task_under_cgroup__destroy(skel);
+}
diff --git
a/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
new file mode 100644
index 000000000000..5bcb726d6d0a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Bytedance */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#include "bpf_misc.h"
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+long bpf_task_under_cgroup(struct task_struct *task, struct cgroup
*ancestor) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+const volatile int local_pid;
+const volatile long cgid;
cgid cannot be a negative number. So let us do
const volatile __u64 cgid;
Ok
+int remote_pid;
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(handle__task_newtask, struct task_struct *task, u64
clone_flags)
+{
+ struct cgroup *cgrp = NULL;
+ struct task_struct *acquired = NULL;
"acquired = NULL" is not needed. Just do "struct task_struct *acquired;".
Ok
+
+ if (local_pid != (bpf_get_current_pid_tgid() >> 32))
+ return 0;
+
+ acquired = bpf_task_acquire(task);
+ if (!acquired)
+ return 0;
+
+ if (local_pid == acquired->tgid)
+ goto out;
+
+ cgrp = bpf_cgroup_from_id(cgid);
+ if (!cgrp)
+ goto out;
+
+ if (bpf_task_under_cgroup(acquired, cgrp))
+ remote_pid = acquired->tgid;
+
+out:
+ if (acquired)
+ bpf_task_release(acquired);
+ if (cgrp)
+ bpf_cgroup_release(cgrp);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";