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From:   Song Liu <songliubraving@fb.com>
To:     <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <ast@kernel.org>, <daniel@iogearbox.net>, <kernel-team@fb.com>,
        <peterz@infradead.org>, Song Liu <songliubraving@fb.com>
Subject: [PATCH v6 bpf-next 3/6] selftests/bpf: add non-BPF_LSM test for task local storage
Date:   Thu, 25 Feb 2021 15:43:16 -0800
Message-ID: <20210225234319.336131-4-songliubraving@fb.com>
In-Reply-To: <20210225234319.336131-1-songliubraving@fb.com>
References: <20210225234319.336131-1-songliubraving@fb.com>
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Task local storage is enabled for tracing programs. Add two tests for
task local storage without CONFIG_BPF_LSM.

The first test stores a value in sys_enter and read it back in sys_exit.

The second test checks whether the kernel allows allocating task local
storage in exit_creds() (which it should not).

Signed-off-by: Song Liu <songliubraving@fb.com>
---
 .../bpf/prog_tests/task_local_storage.c       | 69 +++++++++++++++++++
 .../selftests/bpf/progs/task_local_storage.c  | 64 +++++++++++++++++
 .../bpf/progs/task_local_storage_exit_creds.c | 32 +++++++++
 3 files changed, 165 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/task_local_sto=
rage.c
 create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage.=
c
 create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage_=
exit_creds.c

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c =
b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
new file mode 100644
index 0000000000000..dbb7525cdd567
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#define _GNU_SOURCE         /* See feature_test_macros(7) */
+#include <unistd.h>
+#include <sys/syscall.h>   /* For SYS_xxx definitions */
+#include <sys/types.h>
+#include <test_progs.h>
+#include "task_local_storage.skel.h"
+#include "task_local_storage_exit_creds.skel.h"
+
+static void test_sys_enter_exit(void)
+{
+	struct task_local_storage *skel;
+	int err;
+
+	skel =3D task_local_storage__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	skel->bss->target_pid =3D syscall(SYS_gettid);
+
+	err =3D task_local_storage__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto out;
+
+	syscall(SYS_gettid);
+	syscall(SYS_gettid);
+
+	/* 3x syscalls: 1x attach and 2x gettid */
+	ASSERT_EQ(skel->bss->enter_cnt, 3, "enter_cnt");
+	ASSERT_EQ(skel->bss->exit_cnt, 3, "exit_cnt");
+	ASSERT_EQ(skel->bss->mismatch_cnt, 0, "mismatch_cnt");
+out:
+	task_local_storage__destroy(skel);
+}
+
+static void test_exit_creds(void)
+{
+	struct task_local_storage_exit_creds *skel;
+	int err;
+
+	skel =3D task_local_storage_exit_creds__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	err =3D task_local_storage_exit_creds__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto out;
+
+	/* trigger at least one exit_creds() */
+	if (CHECK_FAIL(system("ls > /dev/null")))
+		goto out;
+
+	/* sync rcu to make sure exit_creds() is called for "ls" */
+	kern_sync_rcu();
+	ASSERT_EQ(skel->bss->valid_ptr_count, 0, "valid_ptr_count");
+	ASSERT_NEQ(skel->bss->null_ptr_count, 0, "null_ptr_count");
+out:
+	task_local_storage_exit_creds__destroy(skel);
+}
+
+void test_task_local_storage(void)
+{
+	if (test__start_subtest("sys_enter_exit"))
+		test_sys_enter_exit();
+	if (test__start_subtest("exit_creds"))
+		test_exit_creds();
+}
diff --git a/tools/testing/selftests/bpf/progs/task_local_storage.c b/too=
ls/testing/selftests/bpf/progs/task_local_storage.c
new file mode 100644
index 0000000000000..80a0a20db88d2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_local_storage.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") =3D "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, long);
+} enter_id SEC(".maps");
+
+#define MAGIC_VALUE 0xabcd1234
+
+pid_t target_pid =3D 0;
+int mismatch_cnt =3D 0;
+int enter_cnt =3D 0;
+int exit_cnt =3D 0;
+
+SEC("tp_btf/sys_enter")
+int BPF_PROG(on_enter, struct pt_regs *regs, long id)
+{
+	struct task_struct *task;
+	long *ptr;
+
+	task =3D bpf_get_current_task_btf();
+	if (task->pid !=3D target_pid)
+		return 0;
+
+	ptr =3D bpf_task_storage_get(&enter_id, task, 0,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!ptr)
+		return 0;
+
+	__sync_fetch_and_add(&enter_cnt, 1);
+	*ptr =3D MAGIC_VALUE + enter_cnt;
+
+	return 0;
+}
+
+SEC("tp_btf/sys_exit")
+int BPF_PROG(on_exit, struct pt_regs *regs, long id)
+{
+	struct task_struct *task;
+	long *ptr;
+
+	task =3D bpf_get_current_task_btf();
+	if (task->pid !=3D target_pid)
+		return 0;
+
+	ptr =3D bpf_task_storage_get(&enter_id, task, 0,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!ptr)
+		return 0;
+
+	__sync_fetch_and_add(&exit_cnt, 1);
+	if (*ptr !=3D MAGIC_VALUE + exit_cnt)
+		__sync_fetch_and_add(&mismatch_cnt, 1);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/task_local_storage_exit_cr=
eds.c b/tools/testing/selftests/bpf/progs/task_local_storage_exit_creds.c
new file mode 100644
index 0000000000000..81758c0aef993
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_local_storage_exit_creds.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") =3D "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, __u64);
+} task_storage SEC(".maps");
+
+int valid_ptr_count =3D 0;
+int null_ptr_count =3D 0;
+
+SEC("fentry/exit_creds")
+int BPF_PROG(trace_exit_creds, struct task_struct *task)
+{
+	__u64 *ptr;
+
+	ptr =3D bpf_task_storage_get(&task_storage, task, 0,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (ptr)
+		__sync_fetch_and_add(&valid_ptr_count, 1);
+	else
+		__sync_fetch_and_add(&null_ptr_count, 1);
+	return 0;
+}
--=20
2.24.1