在 2023/5/4 22:46, Yonghong Song 写道:

On 5/3/23 8:15 PM, Feng zhou wrote:

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From: Feng Zhou zhoufeng.zf@bytedance.com

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@bytedance.com

Ack with a few nits below. You can carry my Ack in the next revision.

Acked-by: Yonghong Song yhs@fb.com

Will do

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---

tools/testing/selftests/bpf/DENYLIST.s390x    |  1 +   .../bpf/prog_tests/task_under_cgroup.c        | 54 +++++++++++++++++++   .../bpf/progs/test_task_under_cgroup.c        | 51 ++++++++++++++++++   3 files changed, 106 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..fa3a98eae5ef --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c @@ -0,0 +1,54 @@ +// 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;

You do not need to initialize 'foo' here.

...

+    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);

+    ret = (pid == -1); +    if (ASSERT_OK(ret, "fork process")) +        wait(NULL);

+    test_task_under_cgroup__detach(skel);

+    ASSERT_NEQ(skel->bss->remote_pid, skel->rodata->local_pid, +           "test task_under_cgroup");

+cleanup: +    close(foo);

+    test_task_under_cgroup__destroy(skel);

Let us just do: cleanup:     test_task_under_cgroup__destroy(skel);     close(foo);

This is the reverse order of test__join_cgroup() and test_task_under_cgroup__open().

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+} 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..79d98e65c7eb --- /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 __u64 cgid; +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;

+    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);

Let us do: out:     if (cgrp)         bpf_cgroup_release(cgrp);     bpf_task_release(acquired);

...

+    return 0; +}

+char _license[] SEC("license") = "GPL";