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 <void@xxxxxxxxxxxxx>
---
tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
.../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 072243af93b0..f70a677b38e5 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 000000000000..c1bcd7da9da8
--- /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 <sys/wait.h>
+#include <test_progs.h>
+#include <unistd.h>
+
+#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", "release kernel function bpf_task_release expects"},
+ {"task_kfunc_release_fp", "arg#0 pointer type STRUCT task_struct must point"},
+ {"task_kfunc_release_null", "R0 release reg has unsafe modifiers"},
+ {"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 000000000000..160d6dde00be
--- /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 <errno.h>
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+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 000000000000..93e934ddfcb6
--- /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 <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#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 000000000000..be4534b5ba2e
--- /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 <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#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;
+}
--
2.38.1
