Commit 48671232 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for bpf_rcu_read_lock() 



Add a few positive/negative tests to test bpf_rcu_read_lock()
and its corresponding verifier support. The new test will fail
on s390x and aarch64, so an entry is added to each of their
respective deny lists.

Acked-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221124053222.2374650-1-yhs@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9bb00b28

tools/testing/selftests/bpf/DENYLIST.aarch64

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ modify_return # modify_return__attach failed 
module_attach                                    # skel_attach skeleton attach failed: -524

mptcp/base                                       # run_test mptcp unexpected error: -524 (errno 524)

netcnt                                           # packets unexpected packets: actual 10001 != expected 10000

rcu_read_lock                                    # failed to attach: ERROR: strerror_r(-524)=22

recursion                                        # skel_attach unexpected error: -524 (errno 524)

ringbuf                                          # skel_attach skeleton attachment failed: -1

setget_sockopt                                   # attach_cgroup unexpected error: -524

tools/testing/selftests/bpf/DENYLIST.s390x

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ module_attach # skel_attach skeleton attach failed: - 
mptcp

netcnt                                   # failed to load BPF skeleton 'netcnt_prog': -7                               (?)

probe_user                               # check_kprobe_res wrong kprobe res from probe read                           (?)

rcu_read_lock                            # failed to find kernel BTF type ID of '__x64_sys_getpgid': -3                (?)

recursion                                # skel_attach unexpected error: -524                                          (trampoline)

ringbuf                                  # skel_load skeleton load failed                                              (?)

select_reuseport                         # intermittently fails on new s390x setup

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

0 → 100644
+158 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.*/



#define _GNU_SOURCE

#include <unistd.h>

#include <sys/syscall.h>

#include <sys/types.h>

#include <test_progs.h>

#include <bpf/btf.h>

#include "rcu_read_lock.skel.h"

#include "cgroup_helpers.h"



static unsigned long long cgroup_id;



static void test_success(void)

{

	struct rcu_read_lock *skel;

	int err;



	skel = rcu_read_lock__open();

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

		return;



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



	bpf_program__set_autoload(skel->progs.get_cgroup_id, true);

	bpf_program__set_autoload(skel->progs.task_succ, true);

	bpf_program__set_autoload(skel->progs.no_lock, true);

	bpf_program__set_autoload(skel->progs.two_regions, true);

	bpf_program__set_autoload(skel->progs.non_sleepable_1, true);

	bpf_program__set_autoload(skel->progs.non_sleepable_2, true);

	err = rcu_read_lock__load(skel);

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

		goto out;



	err = rcu_read_lock__attach(skel);

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

		goto out;



	syscall(SYS_getpgid);



	ASSERT_EQ(skel->bss->task_storage_val, 2, "task_storage_val");

	ASSERT_EQ(skel->bss->cgroup_id, cgroup_id, "cgroup_id");

out:

	rcu_read_lock__destroy(skel);

}



static void test_rcuptr_acquire(void)

{

	struct rcu_read_lock *skel;

	int err;



	skel = rcu_read_lock__open();

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

		return;



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



	bpf_program__set_autoload(skel->progs.task_acquire, true);

	err = rcu_read_lock__load(skel);

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

		goto out;



	err = rcu_read_lock__attach(skel);

	ASSERT_OK(err, "skel_attach");

out:

	rcu_read_lock__destroy(skel);

}



static const char * const inproper_region_tests[] = {

	"miss_lock",

	"miss_unlock",

	"non_sleepable_rcu_mismatch",

	"inproper_sleepable_helper",

	"inproper_sleepable_kfunc",

	"nested_rcu_region",

};



static void test_inproper_region(void)

{

	struct rcu_read_lock *skel;

	struct bpf_program *prog;

	int i, err;



	for (i = 0; i < ARRAY_SIZE(inproper_region_tests); i++) {

		skel = rcu_read_lock__open();

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

			return;



		prog = bpf_object__find_program_by_name(skel->obj, inproper_region_tests[i]);

		if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))

			goto out;

		bpf_program__set_autoload(prog, true);

		err = rcu_read_lock__load(skel);

		ASSERT_ERR(err, "skel_load");

out:

		rcu_read_lock__destroy(skel);

	}

}



static const char * const rcuptr_misuse_tests[] = {

	"task_untrusted_non_rcuptr",

	"task_untrusted_rcuptr",

	"cross_rcu_region",

};



static void test_rcuptr_misuse(void)

{

	struct rcu_read_lock *skel;

	struct bpf_program *prog;

	int i, err;



	for (i = 0; i < ARRAY_SIZE(rcuptr_misuse_tests); i++) {

		skel = rcu_read_lock__open();

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

			return;



		prog = bpf_object__find_program_by_name(skel->obj, rcuptr_misuse_tests[i]);

		if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))

			goto out;

		bpf_program__set_autoload(prog, true);

		err = rcu_read_lock__load(skel);

		ASSERT_ERR(err, "skel_load");

out:

		rcu_read_lock__destroy(skel);

	}

}



void test_rcu_read_lock(void)

{

	struct btf *vmlinux_btf;

	int cgroup_fd;



	vmlinux_btf = btf__load_vmlinux_btf();

	if (!ASSERT_OK_PTR(vmlinux_btf, "could not load vmlinux BTF"))

		return;

	if (btf__find_by_name_kind(vmlinux_btf, "rcu", BTF_KIND_TYPE_TAG) < 0) {

		test__skip();

		goto out;

	}



	cgroup_fd = test__join_cgroup("/rcu_read_lock");

	if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup /rcu_read_lock"))

		goto out;



	cgroup_id = get_cgroup_id("/rcu_read_lock");

	if (test__start_subtest("success"))

		test_success();

	if (test__start_subtest("rcuptr_acquire"))

		test_rcuptr_acquire();

	if (test__start_subtest("negative_tests_inproper_region"))

		test_inproper_region();

	if (test__start_subtest("negative_tests_rcuptr_misuse"))

		test_rcuptr_misuse();

	close(cgroup_fd);

out:

	btf__free(vmlinux_btf);

}

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

0 → 100644
+290 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include "bpf_tracing_net.h"

#include "bpf_misc.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);

} map_a SEC(".maps");



__u32 user_data, key_serial, target_pid;

__u64 flags, task_storage_val, cgroup_id;



struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;

void bpf_key_put(struct bpf_key *key) __ksym;

void bpf_rcu_read_lock(void) __ksym;

void bpf_rcu_read_unlock(void) __ksym;

struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;

void bpf_task_release(struct task_struct *p) __ksym;



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int get_cgroup_id(void *ctx)

{

	struct task_struct *task;



	task = bpf_get_current_task_btf();

	if (task->pid != target_pid)

		return 0;



	/* simulate bpf_get_current_cgroup_id() helper */

	bpf_rcu_read_lock();

	cgroup_id = task->cgroups->dfl_cgrp->kn->id;

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int task_succ(void *ctx)

{

	struct task_struct *task, *real_parent;

	long init_val = 2;

	long *ptr;



	task = bpf_get_current_task_btf();

	if (task->pid != target_pid)

		return 0;



	bpf_rcu_read_lock();

	/* region including helper using rcu ptr real_parent */

	real_parent = task->real_parent;

	ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,

				   BPF_LOCAL_STORAGE_GET_F_CREATE);

	if (!ptr)

		goto out;

	ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);

	if (!ptr)

		goto out;

	task_storage_val = *ptr;

out:

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")

int no_lock(void *ctx)

{

	struct task_struct *task, *real_parent;



	/* no bpf_rcu_read_lock(), old code still works */

	task = bpf_get_current_task_btf();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")

int two_regions(void *ctx)

{

	struct task_struct *task, *real_parent;



	/* two regions */

	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	bpf_rcu_read_unlock();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry/" SYS_PREFIX "sys_getpgid")

int non_sleepable_1(void *ctx)

{

	struct task_struct *task, *real_parent;



	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry/" SYS_PREFIX "sys_getpgid")

int non_sleepable_2(void *ctx)

{

	struct task_struct *task, *real_parent;



	bpf_rcu_read_lock();

	task = bpf_get_current_task_btf();

	bpf_rcu_read_unlock();



	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")

int task_acquire(void *ctx)

{

	struct task_struct *task, *real_parent;



	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	/* acquire a reference which can be used outside rcu read lock region */

	real_parent = bpf_task_acquire(real_parent);

	bpf_rcu_read_unlock();

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_task_release(real_parent);

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int miss_lock(void *ctx)

{

	struct task_struct *task;

	struct css_set *cgroups;

	struct cgroup *dfl_cgrp;



	/* missing bpf_rcu_read_lock() */

	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	(void)bpf_task_storage_get(&map_a, task, 0, 0);

	bpf_rcu_read_unlock();

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int miss_unlock(void *ctx)

{

	struct task_struct *task;

	struct css_set *cgroups;

	struct cgroup *dfl_cgrp;



	/* missing bpf_rcu_read_unlock() */

	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	(void)bpf_task_storage_get(&map_a, task, 0, 0);

	return 0;

}



SEC("?fentry/" SYS_PREFIX "sys_getpgid")

int non_sleepable_rcu_mismatch(void *ctx)

{

	struct task_struct *task, *real_parent;



	task = bpf_get_current_task_btf();

	/* non-sleepable: missing bpf_rcu_read_unlock() in one path */

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	if (real_parent)

		bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int inproper_sleepable_helper(void *ctx)

{

	struct task_struct *task, *real_parent;

	struct pt_regs *regs;

	__u32 value = 0;

	void *ptr;



	task = bpf_get_current_task_btf();

	/* sleepable helper in rcu read lock region */

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);

	if (!regs) {

		bpf_rcu_read_unlock();

		return 0;

	}



	ptr = (void *)PT_REGS_IP(regs);

	(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);

	user_data = value;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?lsm.s/bpf")

int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)

{

	struct bpf_key *bkey;



	/* sleepable kfunc in rcu read lock region */

	bpf_rcu_read_lock();

	bkey = bpf_lookup_user_key(key_serial, flags);

	bpf_rcu_read_unlock();

	if (!bkey)

		return -1;

	bpf_key_put(bkey);



	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")

int nested_rcu_region(void *ctx)

{

	struct task_struct *task, *real_parent;



	/* nested rcu read lock regions */

	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int task_untrusted_non_rcuptr(void *ctx)

{

	struct task_struct *task, *last_wakee;



	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	/* the pointer last_wakee marked as untrusted */

	last_wakee = task->real_parent->last_wakee;

	(void)bpf_task_storage_get(&map_a, last_wakee, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")

int task_untrusted_rcuptr(void *ctx)

{

	struct task_struct *task, *real_parent;



	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	bpf_rcu_read_unlock();

	/* helper use of rcu ptr outside the rcu read lock region */

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	return 0;

}



SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")

int cross_rcu_region(void *ctx)

{

	struct task_struct *task, *real_parent;



	/* rcu ptr define/use in different regions */

	task = bpf_get_current_task_btf();

	bpf_rcu_read_lock();

	real_parent = task->real_parent;

	bpf_rcu_read_unlock();

	bpf_rcu_read_lock();

	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);

	bpf_rcu_read_unlock();

	return 0;

}