[bpf-next,v5,8/8] selftests/bpf: Add tests for open-coded task and css iter

Message ID 20231011120857.251943-9-zhouchuyi@bytedance.com
State New
Headers
Series Add Open-coded task, css_task and css iters |

Commit Message

Chuyi Zhou Oct. 11, 2023, 12:08 p.m. UTC
  This patch adds three subtests to demonstrate these patterns and validating
correctness.

subtest1:

1) We use task_iter to iterate all process in the system and search for the
current process with a given pid.

2) We create some threads in current process context, and use
BPF_TASK_ITER_PROC_THREADS to iterate all threads of current process. As
expected, we would find all the threads of current process.

3) We create some threads and use BPF_TASK_ITER_ALL_THREADS to iterate all
threads in the system. As expected, we would find all the threads which was
created.

subtest2: We create a cgroup and add the current task to the cgroup. In the
BPF program, we would use bpf_for_each(css_task, task, css) to iterate all
tasks under the cgroup. As expected, we would find the current process.

subtest3:

1) We create a cgroup tree. In the BPF program, we use
bpf_for_each(css, pos, root, XXX) to iterate all descendant under the root
with pre and post order. As expected, we would find all descendant and the
last iterating cgroup in post-order is root cgroup, the first iterating
cgroup in pre-order is root cgroup.

2) We wse BPF_CGROUP_ITER_ANCESTORS_UP to traverse the cgroup tree starting
from leaf and root separately, and record the height. The diff of the
hights would be the total tree-high - 1.

Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
---
 .../testing/selftests/bpf/prog_tests/iters.c  | 161 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/iters_css.c |  74 ++++++++
 .../selftests/bpf/progs/iters_css_task.c      |  42 +++++
 .../testing/selftests/bpf/progs/iters_task.c  |  41 +++++
 .../selftests/bpf/progs/iters_task_failure.c  | 105 ++++++++++++
 5 files changed, 423 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/iters_css.c
 create mode 100644 tools/testing/selftests/bpf/progs/iters_css_task.c
 create mode 100644 tools/testing/selftests/bpf/progs/iters_task.c
 create mode 100644 tools/testing/selftests/bpf/progs/iters_task_failure.c
  

Comments

Chuyi Zhou Oct. 12, 2023, 2:38 a.m. UTC | #1
在 2023/10/11 20:08, Chuyi Zhou 写道:
> This patch adds three subtests to demonstrate these patterns and validating
> correctness.
> 
> subtest1:
> 
> 1) We use task_iter to iterate all process in the system and search for the
> current process with a given pid.
> 
> 2) We create some threads in current process context, and use
> BPF_TASK_ITER_PROC_THREADS to iterate all threads of current process. As
> expected, we would find all the threads of current process.
> 
> 3) We create some threads and use BPF_TASK_ITER_ALL_THREADS to iterate all
> threads in the system. As expected, we would find all the threads which was
> created.
> 
> subtest2: We create a cgroup and add the current task to the cgroup. In the
> BPF program, we would use bpf_for_each(css_task, task, css) to iterate all
> tasks under the cgroup. As expected, we would find the current process.
> 
> subtest3:
> 
> 1) We create a cgroup tree. In the BPF program, we use
> bpf_for_each(css, pos, root, XXX) to iterate all descendant under the root
> with pre and post order. As expected, we would find all descendant and the
> last iterating cgroup in post-order is root cgroup, the first iterating
> cgroup in pre-order is root cgroup.
> 
> 2) We wse BPF_CGROUP_ITER_ANCESTORS_UP to traverse the cgroup tree starting
> from leaf and root separately, and record the height. The diff of the
> hights would be the total tree-high - 1.
> 
> Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
> ---
>   .../testing/selftests/bpf/prog_tests/iters.c  | 161 ++++++++++++++++++
>   tools/testing/selftests/bpf/progs/iters_css.c |  74 ++++++++
>   .../selftests/bpf/progs/iters_css_task.c      |  42 +++++
>   .../testing/selftests/bpf/progs/iters_task.c  |  41 +++++
>   .../selftests/bpf/progs/iters_task_failure.c  | 105 ++++++++++++
>   5 files changed, 423 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/iters_css.c
>   create mode 100644 tools/testing/selftests/bpf/progs/iters_css_task.c
>   create mode 100644 tools/testing/selftests/bpf/progs/iters_task.c
>   create mode 100644 tools/testing/selftests/bpf/progs/iters_task_failure.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
> index 10804ae5ae97..8d7a7bef5c73 100644
> --- a/tools/testing/selftests/bpf/prog_tests/iters.c
> +++ b/tools/testing/selftests/bpf/prog_tests/iters.c
> @@ -1,13 +1,24 @@
>   // SPDX-License-Identifier: GPL-2.0
>   /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
>   
> +#include <sys/syscall.h>
> +#include <sys/mman.h>
> +#include <sys/wait.h>
> +#include <unistd.h>
> +#include <malloc.h>
> +#include <stdlib.h>
>   #include <test_progs.h>
> +#include "cgroup_helpers.h"
>   
>   #include "iters.skel.h"
>   #include "iters_state_safety.skel.h"
>   #include "iters_looping.skel.h"
>   #include "iters_num.skel.h"
>   #include "iters_testmod_seq.skel.h"
> +#include "iters_task.skel.h"
> +#include "iters_css_task.skel.h"
> +#include "iters_css.skel.h"
> +#include "iters_task_failure.skel.h"
>   
>   static void subtest_num_iters(void)
>   {
> @@ -90,6 +101,149 @@ static void subtest_testmod_seq_iters(void)
>   	iters_testmod_seq__destroy(skel);
>   }
>   
> +static pthread_mutex_t do_nothing_mutex;
> +
> +static void *do_nothing_wait(void *arg)
> +{
> +	pthread_mutex_lock(&do_nothing_mutex);
> +	pthread_mutex_unlock(&do_nothing_mutex);
> +
> +	pthread_exit(arg);
> +}
> +
> +#define thread_num 2
> +
> +static void subtest_task_iters(void)
> +{
> +	struct iters_task *skel = NULL;
> +	pthread_t thread_ids[thread_num];
> +	void *ret;
> +	int err;
> +
> +	skel = iters_task__open();
> +	if (!ASSERT_OK_PTR(skel, "skel_open"))
> +		goto cleanup;
> +	err = iters_task__load(skel);
> +	if (!ASSERT_OK(err, "skel_load"))
> +		goto cleanup;
> +	skel->bss->target_pid = getpid();
> +	err = iters_task__attach(skel);
> +	if (!ASSERT_OK(err, "iters_task__attach"))
> +		goto cleanup;
> +	pthread_mutex_lock(&do_nothing_mutex);
> +	for (int i = 0; i < thread_num; i++)
> +		ASSERT_OK(pthread_create(&thread_ids[i], NULL, &do_nothing_wait, NULL),
> +			"pthread_create");
> +
> +	syscall(SYS_getpgid);
> +	iters_task__detach(skel);
> +	ASSERT_EQ(skel->bss->process_cnt, 1, "process_cnt");
> +	ASSERT_EQ(skel->bss->thread_cnt, thread_num + 1, "thread_cnt");
> +	ASSERT_EQ(skel->bss->all_thread_cnt, thread_num + 1, "all_thread_cnt");
> +	pthread_mutex_unlock(&do_nothing_mutex);
> +	for (int i = 0; i < thread_num; i++)
> +		pthread_join(thread_ids[i], &ret);
> +cleanup:
> +	iters_task__destroy(skel);
> +}
> +
> +extern int stack_mprotect(void);
> +
> +static void subtest_css_task_iters(void)
> +{
> +	struct iters_css_task *skel = NULL;
> +	int err, cg_fd, cg_id;
> +	const char *cgrp_path = "/cg1";
> +
> +	err = setup_cgroup_environment();
> +	if (!ASSERT_OK(err, "setup_cgroup_environment"))
> +		goto cleanup;
> +	cg_fd = create_and_get_cgroup(cgrp_path);
> +	if (!ASSERT_GE(cg_fd, 0, "cg_create"))
> +		goto cleanup;
> +	cg_id = get_cgroup_id(cgrp_path);
> +	err = join_cgroup(cgrp_path);
> +	if (!ASSERT_OK(err, "setup_cgroup_environment"))
> +		goto cleanup;
> +
> +	skel = iters_css_task__open();
> +	if (!ASSERT_OK_PTR(skel, "skel_open"))
> +		goto cleanup;
> +
> +	err = iters_css_task__load(skel);
> +	if (!ASSERT_OK(err, "skel_load"))
> +		goto cleanup;
> +
> +	skel->bss->target_pid = getpid();
> +	skel->bss->cg_id = cg_id;
> +	err = iters_css_task__attach(skel);
> +
> +	err = stack_mprotect();
> +	if (!ASSERT_OK(err, "iters_task__attach"))
> +		goto cleanup;

The is incorrect and would fail the lsm_test in prog_test.

Here we should check the stack_mprotect return value is -1 or
-EPERM. In BPF Prog iter_css_task_for_each, we need to return -EPERM.

The whole logic should keep same with lsm_test.c/bpf_cookie.c

After the following fix, CI would works well.

(https://github.com/kernel-patches/bpf/actions/runs/6484774470/job/17609349165?pr=5808)

@@ -177,11 +177,12 @@ static void subtest_css_task_iters(void)
         skel->bss->target_pid = getpid();
         skel->bss->cg_id = cg_id;
         err = iters_css_task__attach(skel);
-
-       err = stack_mprotect();
         if (!ASSERT_OK(err, "iters_task__attach"))
                 goto cleanup;
-
+       err = stack_mprotect();
+       if (!ASSERT_EQ(err, -1, "stack_mprotect") ||
+           !ASSERT_EQ(errno, EPERM, "stack_mprotect"))
+               goto cleanup;
         iters_css_task__detach(skel);
         ASSERT_EQ(skel->bss->css_task_cnt, 1, "css_task_cnt");

diff --git a/tools/testing/selftests/bpf/progs/iters_css_task.c 
b/tools/testing/selftests/bpf/progs/iters_css_task.c
index 506a2755234e..9f79a57fde8e 100644
--- a/tools/testing/selftests/bpf/progs/iters_css_task.c
+++ b/tools/testing/selftests/bpf/progs/iters_css_task.c
@@ -2,6 +2,7 @@
  /* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */

  #include "vmlinux.h"
+#include <errno.h>
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_tracing.h>
  #include "bpf_misc.h"
@@ -17,7 +18,8 @@ int css_task_cnt = 0;
  u64 cg_id;

  SEC("lsm/file_mprotect")
-int BPF_PROG(iter_css_task_for_each)
+int BPF_PROG(iter_css_task_for_each, struct vm_area_struct *vma,
+           unsigned long reqprot, unsigned long prot, int ret)
  {
         struct task_struct *cur_task = bpf_get_current_task_btf();
         struct cgroup_subsys_state *css;
@@ -25,12 +27,12 @@ int BPF_PROG(iter_css_task_for_each)
         struct cgroup *cgrp;

         if (cur_task->pid != target_pid)
-               return 0;
+               return ret;

         cgrp = bpf_cgroup_from_id(cg_id);

-       if (cgrp == NULL)
-               return 0;
+       if (!cgrp)
+               goto out;
         css = &cgrp->self;

         bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS)
@@ -38,5 +40,6 @@ int BPF_PROG(iter_css_task_for_each)
                         css_task_cnt += 1;

         bpf_cgroup_release(cgrp);
-       return 0;
+out:
+       return -EPERM;
  }
  

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index 10804ae5ae97..8d7a7bef5c73 100644
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -1,13 +1,24 @@ 
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
 
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <stdlib.h>
 #include <test_progs.h>
+#include "cgroup_helpers.h"
 
 #include "iters.skel.h"
 #include "iters_state_safety.skel.h"
 #include "iters_looping.skel.h"
 #include "iters_num.skel.h"
 #include "iters_testmod_seq.skel.h"
+#include "iters_task.skel.h"
+#include "iters_css_task.skel.h"
+#include "iters_css.skel.h"
+#include "iters_task_failure.skel.h"
 
 static void subtest_num_iters(void)
 {
@@ -90,6 +101,149 @@  static void subtest_testmod_seq_iters(void)
 	iters_testmod_seq__destroy(skel);
 }
 
+static pthread_mutex_t do_nothing_mutex;
+
+static void *do_nothing_wait(void *arg)
+{
+	pthread_mutex_lock(&do_nothing_mutex);
+	pthread_mutex_unlock(&do_nothing_mutex);
+
+	pthread_exit(arg);
+}
+
+#define thread_num 2
+
+static void subtest_task_iters(void)
+{
+	struct iters_task *skel = NULL;
+	pthread_t thread_ids[thread_num];
+	void *ret;
+	int err;
+
+	skel = iters_task__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		goto cleanup;
+	err = iters_task__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+	skel->bss->target_pid = getpid();
+	err = iters_task__attach(skel);
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+	pthread_mutex_lock(&do_nothing_mutex);
+	for (int i = 0; i < thread_num; i++)
+		ASSERT_OK(pthread_create(&thread_ids[i], NULL, &do_nothing_wait, NULL),
+			"pthread_create");
+
+	syscall(SYS_getpgid);
+	iters_task__detach(skel);
+	ASSERT_EQ(skel->bss->process_cnt, 1, "process_cnt");
+	ASSERT_EQ(skel->bss->thread_cnt, thread_num + 1, "thread_cnt");
+	ASSERT_EQ(skel->bss->all_thread_cnt, thread_num + 1, "all_thread_cnt");
+	pthread_mutex_unlock(&do_nothing_mutex);
+	for (int i = 0; i < thread_num; i++)
+		pthread_join(thread_ids[i], &ret);
+cleanup:
+	iters_task__destroy(skel);
+}
+
+extern int stack_mprotect(void);
+
+static void subtest_css_task_iters(void)
+{
+	struct iters_css_task *skel = NULL;
+	int err, cg_fd, cg_id;
+	const char *cgrp_path = "/cg1";
+
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto cleanup;
+	cg_fd = create_and_get_cgroup(cgrp_path);
+	if (!ASSERT_GE(cg_fd, 0, "cg_create"))
+		goto cleanup;
+	cg_id = get_cgroup_id(cgrp_path);
+	err = join_cgroup(cgrp_path);
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto cleanup;
+
+	skel = iters_css_task__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		goto cleanup;
+
+	err = iters_css_task__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	skel->bss->target_pid = getpid();
+	skel->bss->cg_id = cg_id;
+	err = iters_css_task__attach(skel);
+
+	err = stack_mprotect();
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+
+	iters_css_task__detach(skel);
+	ASSERT_EQ(skel->bss->css_task_cnt, 1, "css_task_cnt");
+
+cleanup:
+	cleanup_cgroup_environment();
+	iters_css_task__destroy(skel);
+}
+
+static void subtest_css_iters(void)
+{
+	struct iters_css *skel = NULL;
+	struct {
+		const char *path;
+		int fd;
+	} cgs[] = {
+		{ "/cg1" },
+		{ "/cg1/cg2" },
+		{ "/cg1/cg2/cg3" },
+		{ "/cg1/cg2/cg3/cg4" },
+	};
+	int err, cg_nr = ARRAY_SIZE(cgs);
+	int i;
+
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto cleanup;
+	for (i = 0; i < cg_nr; i++) {
+		cgs[i].fd = create_and_get_cgroup(cgs[i].path);
+		if (!ASSERT_GE(cgs[i].fd, 0, "cg_create"))
+			goto cleanup;
+	}
+
+	skel = iters_css__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		goto cleanup;
+	err = iters_css__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	skel->bss->target_pid = getpid();
+	skel->bss->root_cg_id = get_cgroup_id(cgs[0].path);
+	skel->bss->leaf_cg_id = get_cgroup_id(cgs[cg_nr - 1].path);
+	err = iters_css__attach(skel);
+
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+
+	syscall(SYS_getpgid);
+	ASSERT_EQ(skel->bss->pre_css_dec_cnt, cg_nr, "pre order search dec count");
+	ASSERT_EQ(skel->bss->first_cg_id, get_cgroup_id(cgs[0].path),
+				"pre order search first cgroup id");
+
+	ASSERT_EQ(skel->bss->post_css_dec_cnt, cg_nr, "post order search dec count");
+	ASSERT_EQ(skel->bss->last_cg_id, get_cgroup_id(cgs[0].path),
+				"post order search last cgroup id");
+	ASSERT_EQ(skel->bss->tree_high, cg_nr - 1, "tree high");
+	iters_css__detach(skel);
+cleanup:
+	cleanup_cgroup_environment();
+	iters_css__destroy(skel);
+}
+
 void test_iters(void)
 {
 	RUN_TESTS(iters_state_safety);
@@ -103,4 +257,11 @@  void test_iters(void)
 		subtest_num_iters();
 	if (test__start_subtest("testmod_seq"))
 		subtest_testmod_seq_iters();
+	if (test__start_subtest("task"))
+		subtest_task_iters();
+	if (test__start_subtest("css_task"))
+		subtest_css_task_iters();
+	if (test__start_subtest("css"))
+		subtest_css_iters();
+	RUN_TESTS(iters_task_failure);
 }
diff --git a/tools/testing/selftests/bpf/progs/iters_css.c b/tools/testing/selftests/bpf/progs/iters_css.c
new file mode 100644
index 000000000000..1422a7956c44
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_css.c
@@ -0,0 +1,74 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+pid_t target_pid = 0;
+u64 root_cg_id;
+u64 leaf_cg_id;
+
+u64 last_cg_id = 0;
+u64 first_cg_id = 0;
+
+int post_css_dec_cnt = 0;
+int pre_css_dec_cnt = 0;
+int tree_high = 0;
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
+int iter_css_for_each(const void *ctx)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct cgroup_subsys_state *root_css, *leaf_css, *pos;
+	struct cgroup *root_cgrp, *leaf_cgrp, *cur_cgrp;
+
+	if (cur_task->pid != target_pid)
+		return 0;
+
+	root_cgrp = bpf_cgroup_from_id(root_cg_id);
+
+	if (!root_cgrp)
+		return 0;
+
+	leaf_cgrp = bpf_cgroup_from_id(leaf_cg_id);
+
+	if (!leaf_cgrp) {
+		bpf_cgroup_release(root_cgrp);
+		return 0;
+	}
+	root_css = &root_cgrp->self;
+	leaf_css = &leaf_cgrp->self;
+	bpf_rcu_read_lock();
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+		cur_cgrp = pos->cgroup;
+		post_css_dec_cnt += 1;
+		last_cg_id = cur_cgrp->kn->id;
+	}
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {
+		cur_cgrp = pos->cgroup;
+		pre_css_dec_cnt += 1;
+		if (!first_cg_id)
+			first_cg_id = cur_cgrp->kn->id;
+	}
+
+	bpf_for_each(css, pos, leaf_css, BPF_CGROUP_ITER_ANCESTORS_UP)
+		tree_high += 1;
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)
+		tree_high -= 1;
+	bpf_rcu_read_unlock();
+	bpf_cgroup_release(root_cgrp);
+	bpf_cgroup_release(leaf_cgrp);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_css_task.c b/tools/testing/selftests/bpf/progs/iters_css_task.c
new file mode 100644
index 000000000000..506a2755234e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_css_task.c
@@ -0,0 +1,42 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+
+pid_t target_pid = 0;
+int css_task_cnt = 0;
+u64 cg_id;
+
+SEC("lsm/file_mprotect")
+int BPF_PROG(iter_css_task_for_each)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct cgroup_subsys_state *css;
+	struct task_struct *task;
+	struct cgroup *cgrp;
+
+	if (cur_task->pid != target_pid)
+		return 0;
+
+	cgrp = bpf_cgroup_from_id(cg_id);
+
+	if (cgrp == NULL)
+		return 0;
+	css = &cgrp->self;
+
+	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS)
+		if (task->pid == target_pid)
+			css_task_cnt += 1;
+
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_task.c b/tools/testing/selftests/bpf/progs/iters_task.c
new file mode 100644
index 000000000000..bd6d4f7b5e59
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_task.c
@@ -0,0 +1,41 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+pid_t target_pid = 0;
+int process_cnt = 0;
+int thread_cnt = 0;
+int all_thread_cnt = 0;
+
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
+int iter_task_for_each_sleep(void *ctx)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct task_struct *pos;
+
+	if (cur_task->pid != target_pid)
+		return 0;
+	bpf_rcu_read_lock();
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS)
+		if (pos->pid == target_pid)
+			process_cnt += 1;
+
+	bpf_for_each(task, pos, cur_task, BPF_TASK_ITER_PROC_THREADS)
+		thread_cnt += 1;
+
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_THREADS)
+		if (pos->tgid == target_pid)
+			all_thread_cnt += 1;
+	bpf_rcu_read_unlock();
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_task_failure.c b/tools/testing/selftests/bpf/progs/iters_task_failure.c
new file mode 100644
index 000000000000..c3bf96a67dba
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_task_failure.c
@@ -0,0 +1,105 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_task_next")
+int BPF_PROG(iter_tasks_without_lock)
+{
+	struct task_struct *pos;
+
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
+
+	}
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_css_next")
+int BPF_PROG(iter_css_without_lock)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *root_css, *pos;
+
+	if (!cgrp)
+		return 0;
+	root_css = &cgrp->self;
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+
+	}
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_task_next")
+int BPF_PROG(iter_tasks_lock_and_unlock)
+{
+	struct task_struct *pos;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
+		bpf_rcu_read_unlock();
+
+		bpf_rcu_read_lock();
+	}
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_css_next")
+int BPF_PROG(iter_css_lock_and_unlock)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *root_css, *pos;
+
+	if (!cgrp)
+		return 0;
+	root_css = &cgrp->self;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+		bpf_rcu_read_unlock();
+
+		bpf_rcu_read_lock();
+	}
+	bpf_rcu_read_unlock();
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("css_task_iter is only allowed in bpf_lsm and bpf iter-s")
+int BPF_PROG(iter_css_task_for_each)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *css;
+	struct task_struct *task;
+
+	if (cgrp == NULL)
+		return 0;
+	css = &cgrp->self;
+
+	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
+
+	}
+	bpf_cgroup_release(cgrp);
+	return 0;
+}