Commit 1f87dcf1 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add non-BPF_LSM test for task local storage 



Task local storage is enabled for tracing programs. Add two tests for
task local storage without CONFIG_BPF_LSM.

The first test stores a value in sys_enter and read it back in sys_exit.

The second test checks whether the kernel allows allocating task local
storage in exit_creds() (which it should not).

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210225234319.336131-4-songliubraving@fb.com
parent bc235cdb

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */



#define _GNU_SOURCE         /* See feature_test_macros(7) */

#include <unistd.h>

#include <sys/syscall.h>   /* For SYS_xxx definitions */

#include <sys/types.h>

#include <test_progs.h>

#include "task_local_storage.skel.h"

#include "task_local_storage_exit_creds.skel.h"



static void test_sys_enter_exit(void)

{

	struct task_local_storage *skel;

	int err;



	skel = task_local_storage__open_and_load();

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

		return;



	skel->bss->target_pid = syscall(SYS_gettid);



	err = task_local_storage__attach(skel);

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

		goto out;



	syscall(SYS_gettid);

	syscall(SYS_gettid);



	/* 3x syscalls: 1x attach and 2x gettid */

	ASSERT_EQ(skel->bss->enter_cnt, 3, "enter_cnt");

	ASSERT_EQ(skel->bss->exit_cnt, 3, "exit_cnt");

	ASSERT_EQ(skel->bss->mismatch_cnt, 0, "mismatch_cnt");

out:

	task_local_storage__destroy(skel);

}



static void test_exit_creds(void)

{

	struct task_local_storage_exit_creds *skel;

	int err;



	skel = task_local_storage_exit_creds__open_and_load();

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

		return;



	err = task_local_storage_exit_creds__attach(skel);

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

		goto out;



	/* trigger at least one exit_creds() */

	if (CHECK_FAIL(system("ls > /dev/null")))

		goto out;



	/* sync rcu to make sure exit_creds() is called for "ls" */

	kern_sync_rcu();

	ASSERT_EQ(skel->bss->valid_ptr_count, 0, "valid_ptr_count");

	ASSERT_NEQ(skel->bss->null_ptr_count, 0, "null_ptr_count");

out:

	task_local_storage_exit_creds__destroy(skel);

}



void test_task_local_storage(void)

{

	if (test__start_subtest("sys_enter_exit"))

		test_sys_enter_exit();

	if (test__start_subtest("exit_creds"))

		test_exit_creds();

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



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



struct {

	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);

	__uint(map_flags, BPF_F_NO_PREALLOC);

	__type(key, int);

	__type(value, long);

} enter_id SEC(".maps");



#define MAGIC_VALUE 0xabcd1234



pid_t target_pid = 0;

int mismatch_cnt = 0;

int enter_cnt = 0;

int exit_cnt = 0;



SEC("tp_btf/sys_enter")

int BPF_PROG(on_enter, struct pt_regs *regs, long id)

{

	struct task_struct *task;

	long *ptr;



	task = bpf_get_current_task_btf();

	if (task->pid != target_pid)

		return 0;



	ptr = bpf_task_storage_get(&enter_id, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (!ptr)

		return 0;



	__sync_fetch_and_add(&enter_cnt, 1);

	*ptr = MAGIC_VALUE + enter_cnt;



	return 0;

}



SEC("tp_btf/sys_exit")

int BPF_PROG(on_exit, struct pt_regs *regs, long id)

{

	struct task_struct *task;

	long *ptr;



	task = bpf_get_current_task_btf();

	if (task->pid != target_pid)

		return 0;



	ptr = bpf_task_storage_get(&enter_id, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (!ptr)

		return 0;



	__sync_fetch_and_add(&exit_cnt, 1);

	if (*ptr != MAGIC_VALUE + exit_cnt)

		__sync_fetch_and_add(&mismatch_cnt, 1);

	return 0;

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



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



struct {

	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);

	__uint(map_flags, BPF_F_NO_PREALLOC);

	__type(key, int);

	__type(value, __u64);

} task_storage SEC(".maps");



int valid_ptr_count = 0;

int null_ptr_count = 0;



SEC("fentry/exit_creds")

int BPF_PROG(trace_exit_creds, struct task_struct *task)

{

	__u64 *ptr;



	ptr = bpf_task_storage_get(&task_storage, task, 0,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (ptr)

		__sync_fetch_and_add(&valid_ptr_count, 1);

	else

		__sync_fetch_and_add(&null_ptr_count, 1);

	return 0;

}