From fe147956fca4604b920e6be652abc9bea8ce8952 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Sat, 19 Nov 2022 23:10:04 -0600 Subject: [PATCH] bpf/selftests: Add selftests for new task kfuncs A previous change added a series of kfuncs for storing struct task_struct objects as referenced kptrs. This patch adds a new task_kfunc test suite for validating their expected behavior. Signed-off-by: David Vernet Link: https://lore.kernel.org/r/20221120051004.3605026-5-void@manifault.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + .../testing/selftests/bpf/prog_tests/task_kfunc.c | 159 +++++++++++++ .../selftests/bpf/progs/task_kfunc_common.h | 71 ++++++ .../selftests/bpf/progs/task_kfunc_failure.c | 260 +++++++++++++++++++++ .../selftests/bpf/progs/task_kfunc_success.c | 149 ++++++++++++ 5 files changed, 640 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_kfunc.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_common.h create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_failure.c create mode 100644 tools/testing/selftests/bpf/progs/task_kfunc_success.c diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index 072243a..f70a677 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -54,6 +54,7 @@ skc_to_unix_sock # could not attach BPF object unexpecte socket_cookie # prog_attach unexpected error: -524 (trampoline) stacktrace_build_id # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2 (?) tailcalls # tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls (?) +task_kfunc # JIT does not support calling kernel function task_local_storage # failed to auto-attach program 'trace_exit_creds': -524 (trampoline) test_bpffs # bpffs test failed 255 (iterator) test_bprm_opts # failed to auto-attach program 'secure_exec': -524 (trampoline) diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c new file mode 100644 index 0000000..4994fe60 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c @@ -0,0 +1,159 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#define _GNU_SOURCE +#include +#include +#include + +#include "task_kfunc_failure.skel.h" +#include "task_kfunc_success.skel.h" + +static size_t log_buf_sz = 1 << 20; /* 1 MB */ +static char obj_log_buf[1048576]; + +static struct task_kfunc_success *open_load_task_kfunc_skel(void) +{ + struct task_kfunc_success *skel; + int err; + + skel = task_kfunc_success__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return NULL; + + skel->bss->pid = getpid(); + + err = task_kfunc_success__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto cleanup; + + return skel; + +cleanup: + task_kfunc_success__destroy(skel); + return NULL; +} + +static void run_success_test(const char *prog_name) +{ + struct task_kfunc_success *skel; + int status; + pid_t child_pid; + struct bpf_program *prog; + struct bpf_link *link = NULL; + + skel = open_load_task_kfunc_skel(); + if (!ASSERT_OK_PTR(skel, "open_load_skel")) + return; + + if (!ASSERT_OK(skel->bss->err, "pre_spawn_err")) + goto cleanup; + + prog = bpf_object__find_program_by_name(skel->obj, prog_name); + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) + goto cleanup; + + link = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(link, "attached_link")) + goto cleanup; + + child_pid = fork(); + if (!ASSERT_GT(child_pid, -1, "child_pid")) + goto cleanup; + if (child_pid == 0) + _exit(0); + waitpid(child_pid, &status, 0); + + ASSERT_OK(skel->bss->err, "post_wait_err"); + +cleanup: + bpf_link__destroy(link); + task_kfunc_success__destroy(skel); +} + +static const char * const success_tests[] = { + "test_task_acquire_release_argument", + "test_task_acquire_release_current", + "test_task_acquire_leave_in_map", + "test_task_xchg_release", + "test_task_get_release", + "test_task_current_acquire_release", +}; + +static struct { + const char *prog_name; + const char *expected_err_msg; +} failure_tests[] = { + {"task_kfunc_acquire_untrusted", "R1 must be referenced or trusted"}, + {"task_kfunc_acquire_fp", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_unsafe_kretprobe", "reg type unsupported for arg#0 function"}, + {"task_kfunc_acquire_trusted_walked", "R1 must be referenced or trusted"}, + {"task_kfunc_acquire_null", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_acquire_unreleased", "Unreleased reference"}, + {"task_kfunc_get_non_kptr_param", "arg#0 expected pointer to map value"}, + {"task_kfunc_get_non_kptr_acquired", "arg#0 expected pointer to map value"}, + {"task_kfunc_get_null", "arg#0 expected pointer to map value"}, + {"task_kfunc_xchg_unreleased", "Unreleased reference"}, + {"task_kfunc_get_unreleased", "Unreleased reference"}, + {"task_kfunc_release_untrusted", "arg#0 is untrusted_ptr_or_null_ expected ptr_ or socket"}, + {"task_kfunc_release_fp", "arg#0 pointer type STRUCT task_struct must point"}, + {"task_kfunc_release_null", "arg#0 is ptr_or_null_ expected ptr_ or socket"}, + {"task_kfunc_release_unacquired", "release kernel function bpf_task_release expects"}, +}; + +static void verify_fail(const char *prog_name, const char *expected_err_msg) +{ + LIBBPF_OPTS(bpf_object_open_opts, opts); + struct task_kfunc_failure *skel; + int err, i; + + opts.kernel_log_buf = obj_log_buf; + opts.kernel_log_size = log_buf_sz; + opts.kernel_log_level = 1; + + skel = task_kfunc_failure__open_opts(&opts); + if (!ASSERT_OK_PTR(skel, "task_kfunc_failure__open_opts")) + goto cleanup; + + for (i = 0; i < ARRAY_SIZE(failure_tests); i++) { + struct bpf_program *prog; + const char *curr_name = failure_tests[i].prog_name; + + prog = bpf_object__find_program_by_name(skel->obj, curr_name); + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) + goto cleanup; + + bpf_program__set_autoload(prog, !strcmp(curr_name, prog_name)); + } + + err = task_kfunc_failure__load(skel); + if (!ASSERT_ERR(err, "unexpected load success")) + goto cleanup; + + if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg), "expected_err_msg")) { + fprintf(stderr, "Expected err_msg: %s\n", expected_err_msg); + fprintf(stderr, "Verifier output: %s\n", obj_log_buf); + } + +cleanup: + task_kfunc_failure__destroy(skel); +} + +void test_task_kfunc(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(success_tests); i++) { + if (!test__start_subtest(success_tests[i])) + continue; + + run_success_test(success_tests[i]); + } + + for (i = 0; i < ARRAY_SIZE(failure_tests); i++) { + if (!test__start_subtest(failure_tests[i].prog_name)) + continue; + + verify_fail(failure_tests[i].prog_name, failure_tests[i].expected_err_msg); + } +} diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_common.h b/tools/testing/selftests/bpf/progs/task_kfunc_common.h new file mode 100644 index 0000000..160d6dd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_common.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#ifndef _TASK_KFUNC_COMMON_H +#define _TASK_KFUNC_COMMON_H + +#include +#include +#include +#include + +struct __tasks_kfunc_map_value { + struct task_struct __kptr_ref * task; +}; + +struct hash_map { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, int); + __type(value, struct __tasks_kfunc_map_value); + __uint(max_entries, 1); +} __tasks_kfunc_map SEC(".maps"); + +struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym; +struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) +{ + s32 pid; + long status; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); + if (status) + return NULL; + + return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); +} + +static inline int tasks_kfunc_map_insert(struct task_struct *p) +{ + struct __tasks_kfunc_map_value local, *v; + long status; + struct task_struct *acquired, *old; + s32 pid; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); + if (status) + return status; + + local.task = NULL; + status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); + if (status) + return status; + + v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); + if (!v) { + bpf_map_delete_elem(&__tasks_kfunc_map, &pid); + return -ENOENT; + } + + acquired = bpf_task_acquire(p); + old = bpf_kptr_xchg(&v->task, acquired); + if (old) { + bpf_task_release(old); + return -EEXIST; + } + + return 0; +} + +#endif /* _TASK_KFUNC_COMMON_H */ diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c new file mode 100644 index 0000000..93e934d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include + +#include "task_kfunc_common.h" + +char _license[] SEC("license") = "GPL"; + +/* Prototype for all of the program trace events below: + * + * TRACE_EVENT(task_newtask, + * TP_PROTO(struct task_struct *p, u64 clone_flags) + */ + +static struct __tasks_kfunc_map_value *insert_lookup_task(struct task_struct *task) +{ + int status; + + status = tasks_kfunc_map_insert(task); + if (status) + return NULL; + + return tasks_kfunc_map_value_lookup(task); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + struct __tasks_kfunc_map_value *v; + + v = insert_lookup_task(task); + if (!v) + return 0; + + /* Can't invoke bpf_task_acquire() on an untrusted pointer. */ + acquired = bpf_task_acquire(v->task); + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired, *stack_task = (struct task_struct *)&clone_flags; + + /* Can't invoke bpf_task_acquire() on a random frame pointer. */ + acquired = bpf_task_acquire((struct task_struct *)&stack_task); + bpf_task_release(acquired); + + return 0; +} + +SEC("kretprobe/free_task") +int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + acquired = bpf_task_acquire(task); + /* Can't release a bpf_task_acquire()'d task without a NULL check. */ + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + /* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */ + acquired = bpf_task_acquire(task->last_wakee); + bpf_task_release(acquired); + + return 0; +} + + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + /* Can't invoke bpf_task_acquire() on a NULL pointer. */ + acquired = bpf_task_acquire(NULL); + if (!acquired) + return 0; + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + acquired = bpf_task_acquire(task); + + /* Acquired task is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_non_kptr_param, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + + /* Cannot use bpf_task_kptr_get() on a non-kptr, even on a valid task. */ + kptr = bpf_task_kptr_get(&task); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_non_kptr_acquired, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr, *acquired; + + acquired = bpf_task_acquire(task); + + /* Cannot use bpf_task_kptr_get() on a non-kptr, even if it was acquired. */ + kptr = bpf_task_kptr_get(&acquired); + bpf_task_release(acquired); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_null, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + + /* Cannot use bpf_task_kptr_get() on a NULL pointer. */ + kptr = bpf_task_kptr_get(NULL); + if (!kptr) + return 0; + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + + v = insert_lookup_task(task); + if (!v) + return 0; + + kptr = bpf_kptr_xchg(&v->task, NULL); + if (!kptr) + return 0; + + /* Kptr retrieved from map is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_get_unreleased, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + + v = insert_lookup_task(task); + if (!v) + return 0; + + kptr = bpf_task_kptr_get(&v->task); + if (!kptr) + return 0; + + /* Kptr acquired above is never released. */ + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_untrusted, struct task_struct *task, u64 clone_flags) +{ + struct __tasks_kfunc_map_value *v; + + v = insert_lookup_task(task); + if (!v) + return 0; + + /* Can't invoke bpf_task_release() on an untrusted pointer. */ + bpf_task_release(v->task); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_fp, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired = (struct task_struct *)&clone_flags; + + /* Cannot release random frame pointer. */ + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags) +{ + struct __tasks_kfunc_map_value local, *v; + long status; + struct task_struct *acquired, *old; + s32 pid; + + status = bpf_probe_read_kernel(&pid, sizeof(pid), &task->pid); + if (status) + return 0; + + local.task = NULL; + status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); + if (status) + return status; + + v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); + if (!v) + return -ENOENT; + + acquired = bpf_task_acquire(task); + + old = bpf_kptr_xchg(&v->task, acquired); + + /* old cannot be passed to bpf_task_release() without a NULL check. */ + bpf_task_release(old); + bpf_task_release(old); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_flags) +{ + /* Cannot release trusted task pointer which was not acquired. */ + bpf_task_release(task); + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c new file mode 100644 index 0000000..be4534b --- /dev/null +++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include + +#include "task_kfunc_common.h" + +char _license[] SEC("license") = "GPL"; + +int err, pid; + +/* Prototype for all of the program trace events below: + * + * TRACE_EVENT(task_newtask, + * TP_PROTO(struct task_struct *p, u64 clone_flags) + */ + +static bool is_test_kfunc_task(void) +{ + int cur_pid = bpf_get_current_pid_tgid() >> 32; + + return pid == cur_pid; +} + +static int test_acquire_release(struct task_struct *task) +{ + struct task_struct *acquired; + + acquired = bpf_task_acquire(task); + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags) +{ + if (!is_test_kfunc_task()) + return 0; + + return test_acquire_release(task); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_release_current, struct task_struct *task, u64 clone_flags) +{ + if (!is_test_kfunc_task()) + return 0; + + return test_acquire_release(bpf_get_current_task_btf()); +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_acquire_leave_in_map, struct task_struct *task, u64 clone_flags) +{ + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) + err = 1; + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_xchg_release, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) { + err = 1; + return 0; + } + + v = tasks_kfunc_map_value_lookup(task); + if (!v) { + err = 2; + return 0; + } + + kptr = bpf_kptr_xchg(&v->task, NULL); + if (!kptr) { + err = 3; + return 0; + } + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_get_release, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *kptr; + struct __tasks_kfunc_map_value *v; + long status; + + if (!is_test_kfunc_task()) + return 0; + + status = tasks_kfunc_map_insert(task); + if (status) { + err = 1; + return 0; + } + + v = tasks_kfunc_map_value_lookup(task); + if (!v) { + err = 2; + return 0; + } + + kptr = bpf_task_kptr_get(&v->task); + if (!kptr) { + err = 3; + return 0; + } + + bpf_task_release(kptr); + + return 0; +} + +SEC("tp_btf/task_newtask") +int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *current, *acquired; + + if (!is_test_kfunc_task()) + return 0; + + current = bpf_get_current_task_btf(); + acquired = bpf_task_acquire(current); + bpf_task_release(acquired); + + return 0; +} -- 2.7.4