Commit 130e0f7a authored by Chuyi Zhou's avatar Chuyi Zhou Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for open-coded task and css iter 



This patch adds 4 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.

subtest4:

Add some failure testcase when using css_task, task and css iters, e.g,
unlock when using task-iters to iterate tasks.

Signed-off-by: default avatarChuyi Zhou <zhouchuyi@bytedance.com>
Link: https://lore.kernel.org/r/20231018061746.111364-9-zhouchuyi@bytedance.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent ddab78cb

tools/testing/selftests/bpf/prog_tests/iters.c

+150 −0
Original line number Diff line number Diff line 
// 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"
@@ -9,6 +16,10 @@ 
#include "iters_num.skel.h"

#include "iters_testmod_seq.skel.h"

#include "iters_task_vma.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)

{
@@ -146,6 +157,138 @@ static void subtest_task_vma_iters(void) 
	iters_task_vma__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_and_load();

	if (!ASSERT_OK_PTR(skel, "open_and_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->procs_cnt, 1, "procs_cnt");

	ASSERT_EQ(skel->bss->threads_cnt, thread_num + 1, "threads_cnt");

	ASSERT_EQ(skel->bss->proc_threads_cnt, thread_num + 1, "proc_threads_cnt");

	pthread_mutex_unlock(&do_nothing_mutex);

	for (int i = 0; i < thread_num; i++)

		ASSERT_OK(pthread_join(thread_ids[i], &ret), "pthread_join");

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, "create_and_get_cgroup"))

		goto cleanup;

	cg_id = get_cgroup_id(cgrp_path);

	err = join_cgroup(cgrp_path);

	if (!ASSERT_OK(err, "join_cgroup"))

		goto cleanup;



	skel = iters_css_task__open_and_load();

	if (!ASSERT_OK_PTR(skel, "open_and_load"))

		goto cleanup;



	skel->bss->target_pid = getpid();

	skel->bss->cg_id = cg_id;

	err = iters_css_task__attach(skel);

	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");



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, "create_and_get_cgroup"))

			goto cleanup;

	}



	skel = iters_css__open_and_load();

	if (!ASSERT_OK_PTR(skel, "open_and_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_order_cnt, cg_nr, "pre_order_cnt");

	ASSERT_EQ(skel->bss->first_cg_id, get_cgroup_id(cgs[0].path), "first_cg_id");



	ASSERT_EQ(skel->bss->post_order_cnt, cg_nr, "post_order_cnt");

	ASSERT_EQ(skel->bss->last_cg_id, get_cgroup_id(cgs[0].path), "last_cg_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);
@@ -161,4 +304,11 @@ void test_iters(void) 
		subtest_testmod_seq_iters();

	if (test__start_subtest("task_vma"))

		subtest_task_vma_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);

}

tools/testing/selftests/bpf/progs/iters_css.c

0 → 100644
+72 −0
Original line number Diff line number Diff line 
// 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;

u64 root_cg_id, leaf_cg_id;

u64 first_cg_id, last_cg_id;



int pre_order_cnt, post_order_cnt, tree_high;



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;

	pre_order_cnt = post_order_cnt = tree_high = 0;

	first_cg_id = last_cg_id = 0;



	bpf_rcu_read_lock();

	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {

		cur_cgrp = pos->cgroup;

		post_order_cnt++;

		last_cg_id = cur_cgrp->kn->id;

	}



	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {

		cur_cgrp = pos->cgroup;

		pre_order_cnt++;

		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++;



	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)

		tree_high--;

	bpf_rcu_read_unlock();

	bpf_cgroup_release(root_cgrp);

	bpf_cgroup_release(leaf_cgrp);

	return 0;

}

tools/testing/selftests/bpf/progs/iters_css_task.c

0 → 100644
+47 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* 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"

#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;

int css_task_cnt;

u64 cg_id;



SEC("lsm/file_mprotect")

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;

	struct task_struct *task;

	struct cgroup *cgrp;



	if (cur_task->pid != target_pid)

		return ret;



	cgrp = bpf_cgroup_from_id(cg_id);



	if (!cgrp)

		return -EPERM;



	css = &cgrp->self;

	css_task_cnt = 0;



	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS)

		if (task->pid == target_pid)

			css_task_cnt++;



	bpf_cgroup_release(cgrp);



	return -EPERM;

}

tools/testing/selftests/bpf/progs/iters_task.c

0 → 100644
+41 −0
Original line number Diff line number Diff line 
// 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;

int procs_cnt, threads_cnt, proc_threads_cnt;



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;

	procs_cnt = threads_cnt = proc_threads_cnt = 0;



	bpf_rcu_read_lock();

	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS)

		if (pos->pid == target_pid)

			procs_cnt++;



	bpf_for_each(task, pos, cur_task, BPF_TASK_ITER_PROC_THREADS)

		proc_threads_cnt++;



	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_THREADS)

		if (pos->tgid == target_pid)

			threads_cnt++;

	bpf_rcu_read_unlock();

	return 0;

}

tools/testing/selftests/bpf/progs/iters_task_failure.c

0 → 100644
+105 −0
Original line number Diff line number Diff line 
// 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;

}