From 48671232fcb81b76be13c11b0df7089b16baea57 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Wed, 23 Nov 2022 21:32:22 -0800 Subject: [PATCH] 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 Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20221124053222.2374650-1-yhs@fb.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/DENYLIST.aarch64 | 1 + tools/testing/selftests/bpf/DENYLIST.s390x | 1 + .../selftests/bpf/prog_tests/rcu_read_lock.c | 158 ++++++++++ .../selftests/bpf/progs/rcu_read_lock.c | 290 ++++++++++++++++++ 4 files changed, 450 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c create mode 100644 tools/testing/selftests/bpf/progs/rcu_read_lock.c diff --git a/tools/testing/selftests/bpf/DENYLIST.aarch64 b/tools/testing/selftests/bpf/DENYLIST.aarch64 index affc5aebbf0f..8e77515d56f6 100644 --- a/tools/testing/selftests/bpf/DENYLIST.aarch64 +++ b/tools/testing/selftests/bpf/DENYLIST.aarch64 @@ -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 diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index b9a3d80204c6..648a8a1b6b78 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -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 diff --git a/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c new file mode 100644 index 000000000000..447d8560ecb6 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.*/ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#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); +} diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c new file mode 100644 index 000000000000..94a970076b98 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include "vmlinux.h" +#include +#include +#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; +}