6fcd486b3a
bpf_rcu_read_lock/unlock() are only available in clang compiled kernels. Lack of such key mechanism makes it impossible for sleepable bpf programs to use RCU pointers. Allow bpf_rcu_read_lock/unlock() in GCC compiled kernels (though GCC doesn't support btf_type_tag yet) and allowlist certain field dereferences in important data structures like tast_struct, cgroup, socket that are used by sleepable programs either as RCU pointer or full trusted pointer (which is valid outside of RCU CS). Use BTF_TYPE_SAFE_RCU and BTF_TYPE_SAFE_TRUSTED macros for such tagging. They will be removed once GCC supports btf_type_tag. With that refactor check_ptr_to_btf_access(). Make it strict in enforcing PTR_TRUSTED and PTR_UNTRUSTED while deprecating old PTR_TO_BTF_ID without modifier flags. There is a chance that this strict enforcement might break existing programs (especially on GCC compiled kernels), but this cleanup has to start sooner than later. Note PTR_TO_CTX access still yields old deprecated PTR_TO_BTF_ID. Once it's converted to strict PTR_TRUSTED or PTR_UNTRUSTED the kfuncs and helpers will be able to default to KF_TRUSTED_ARGS. KF_RCU will remain as a weaker version of KF_TRUSTED_ARGS where obj refcnt could be 0. Adjust rcu_read_lock selftest to run on gcc and clang compiled kernels. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/bpf/20230303041446.3630-7-alexei.starovoitov@gmail.com
148 lines
3.6 KiB
C
148 lines
3.6 KiB
C
// 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.two_regions, true);
|
|
bpf_program__set_autoload(skel->progs.non_sleepable_1, true);
|
|
bpf_program__set_autoload(skel->progs.non_sleepable_2, true);
|
|
bpf_program__set_autoload(skel->progs.task_trusted_non_rcuptr, 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",
|
|
"no_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_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)
|
|
{
|
|
int cgroup_fd;
|
|
|
|
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:;
|
|
}
|