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Subject[PATCH v4 bpf-next 3/6] selftests/bpf: add non-BPF_LSM test for task local storage
Date
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_storage.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 = task_local_storage__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+ return;
+
+ skel->bss->target_pid = syscall(SYS_gettid);
+
+ err = 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 = task_local_storage_exit_creds__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+ return;
+
+ err = 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/tools/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") = "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 = 0;
+int mismatch_cnt = 0;
+int enter_cnt = 0;
+int exit_cnt = 0;
+
+SEC("tp_btf/sys_enter")
+int BPF_PROG(on_enter, struct pt_regs *regs, long id)
+{
+ struct task_struct *task;
+ long *ptr;
+
+ task = bpf_get_current_task_btf();
+ if (task->pid != target_pid)
+ return 0;
+
+ ptr = 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 = 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 = bpf_get_current_task_btf();
+ if (task->pid != target_pid)
+ return 0;
+
+ ptr = 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 != 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_creds.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") = "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 = 0;
+int null_ptr_count = 0;
+
+SEC("fentry/exit_creds")
+int BPF_PROG(trace_exit_creds, struct task_struct *task)
+{
+ __u64 *ptr;
+
+ ptr = 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;
+}
--
2.24.1
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