[PATCH bpf-next v2 5/9] selftests/bpf: Add nested trust selftests suite

[David Vernet]

Now that defining trusted fields in a struct is supported, we should add
selftests to verify the behavior. This patch adds a few such testcases.

Signed-off-by: David Vernet <void@xxxxxxxxxxxxx>
---
 tools/testing/selftests/bpf/DENYLIST.s390x    |  1 +
 .../selftests/bpf/prog_tests/nested_trust.c   | 12 +++++++
 .../selftests/bpf/progs/nested_trust_common.h | 12 +++++++
 .../bpf/progs/nested_trust_failure.c          | 33 +++++++++++++++++++
 .../bpf/progs/nested_trust_success.c          | 31 +++++++++++++++++
 5 files changed, 89 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/nested_trust.c
 create mode 100644 tools/testing/selftests/bpf/progs/nested_trust_common.h
 create mode 100644 tools/testing/selftests/bpf/progs/nested_trust_failure.c
 create mode 100644 tools/testing/selftests/bpf/progs/nested_trust_success.c

diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index 96e8371f5c2a..1cf5b94cda30 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -44,6 +44,7 @@ map_kptr                                 # failed to open_and_load program: -524
 modify_return                            # modify_return attach failed: -524                                           (trampoline)
 module_attach                            # skel_attach skeleton attach failed: -524                                    (trampoline)
 mptcp
+nested_trust                             # JIT does not support calling kernel function
 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                (?)
diff --git a/tools/testing/selftests/bpf/prog_tests/nested_trust.c b/tools/testing/selftests/bpf/prog_tests/nested_trust.c
new file mode 100644
index 000000000000..39886f58924e
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/nested_trust.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include "nested_trust_failure.skel.h"
+#include "nested_trust_success.skel.h"
+
+void test_nested_trust(void)
+{
+	RUN_TESTS(nested_trust_success);
+	RUN_TESTS(nested_trust_failure);
+}
diff --git a/tools/testing/selftests/bpf/progs/nested_trust_common.h b/tools/testing/selftests/bpf/progs/nested_trust_common.h
new file mode 100644
index 000000000000..83d33931136e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/nested_trust_common.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#ifndef _NESTED_TRUST_COMMON_H
+#define _NESTED_TRUST_COMMON_H
+
+#include <stdbool.h>
+
+bool bpf_cpumask_test_cpu(unsigned int cpu, const struct cpumask *cpumask) __ksym;
+bool bpf_cpumask_first_zero(const struct cpumask *cpumask) __ksym;
+
+#endif /* _NESTED_TRUST_COMMON_H */
diff --git a/tools/testing/selftests/bpf/progs/nested_trust_failure.c b/tools/testing/selftests/bpf/progs/nested_trust_failure.c
new file mode 100644
index 000000000000..14aff7676436
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/nested_trust_failure.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+#include "nested_trust_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)
+ */
+
+SEC("tp_btf/task_newtask")
+__failure __msg("R2 must be referenced or trusted")
+int BPF_PROG(test_invalid_nested_user_cpus, struct task_struct *task, u64 clone_flags)
+{
+	bpf_cpumask_test_cpu(0, task->user_cpus_ptr);
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("R1 must have zero offset when passed to release func or trusted arg to kfunc")
+int BPF_PROG(test_invalid_nested_offset, struct task_struct *task, u64 clone_flags)
+{
+	bpf_cpumask_first_zero(&task->cpus_mask);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/nested_trust_success.c b/tools/testing/selftests/bpf/progs/nested_trust_success.c
new file mode 100644
index 000000000000..398098d24987
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/nested_trust_success.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+#include "nested_trust_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int pid, err;
+
+static bool is_test_task(void)
+{
+	int cur_pid = bpf_get_current_pid_tgid() >> 32;
+
+	return pid == cur_pid;
+}
+
+SEC("tp_btf/task_newtask")
+__success
+int BPF_PROG(test_read_cpumask, struct task_struct *task, u64 clone_flags)
+{
+	if (!is_test_task())
+		return 0;
+
+	bpf_cpumask_test_cpu(0, task->cpus_ptr);
+	return 0;
+}
-- 
2.39.0