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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: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221124053222.2374650-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2022-11-23 21:32:22 -08:00 committed by Alexei Starovoitov
parent 9bb00b2895
commit 48671232fc
4 changed files with 450 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
tools/testing/selftests/bpf/DENYLIST.aarch64
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@ -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

1
tools/testing/selftests/bpf/DENYLIST.s390x
View File

@ -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

158
tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c Normal file
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@ -0,0 +1,158 @@
// 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);
}

290
tools/testing/selftests/bpf/progs/rcu_read_lock.c Normal file
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@ -0,0 +1,290 @@
// 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;
}