diff mbox series

[v4,3/3] libbpf: Add a test to confirm PT_REGS_PARM4_SYSCALL

Message ID 20220119131209.36092-4-Kenta.Tada@sony.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Fix the incorrect register read for syscalls on x86_64 | expand

Checks

Context Check Description
bpf/vmtest-bpf-next success VM_Test
bpf/vmtest-bpf-next-PR success PR summary
netdev/tree_selection success Not a local patch, async

Commit Message

Kenta Tada Jan. 19, 2022, 1:12 p.m. UTC 
Add a selftest to verify the behavior of PT_REGS_xxx.

Signed-off-by: Kenta Tada <Kenta.Tada@sony.com>
---
 .../bpf/prog_tests/test_bpf_syscall_macro.c   | 49 ++++++++++++++++++
 .../selftests/bpf/progs/bpf_syscall_macro.c   | 51 +++++++++++++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_syscall_macro.c

Comments

Andrii Nakryiko Jan. 19, 2022, 6:37 p.m. UTC | #1 
On Wed, Jan 19, 2022 at 5:14 AM Kenta Tada <Kenta.Tada@sony.com> wrote:
>
> Add a selftest to verify the behavior of PT_REGS_xxx.
>
> Signed-off-by: Kenta Tada <Kenta.Tada@sony.com>
> ---
>  .../bpf/prog_tests/test_bpf_syscall_macro.c   | 49 ++++++++++++++++++
>  .../selftests/bpf/progs/bpf_syscall_macro.c   | 51 +++++++++++++++++++
>  2 files changed, 100 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
>  create mode 100644 tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c b/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
> new file mode 100644
> index 000000000000..2f725393195b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright 2022 Sony Group Corporation */
> +#include <sys/prctl.h>
> +#include <test_progs.h>
> +#include "bpf_syscall_macro.skel.h"
> +
> +//void serial_bpf_syscall_macro(void)

leftover

> +void test_bpf_syscall_macro(void)
> +{
> +       struct bpf_syscall_macro *skel = NULL;
> +       int err;
> +       int exp_arg1 = 1001;
> +       unsigned long exp_arg2 = 12;
> +       unsigned long exp_arg3 = 13;
> +       unsigned long exp_arg4 = 14;
> +       unsigned long exp_arg5 = 15;
> +
> +       /* check whether it can open program */
> +       skel = bpf_syscall_macro__open();
> +       if (!ASSERT_OK_PTR(skel, "bpf_syscall_macro__open"))
> +               return;
> +
> +       skel->rodata->filter_pid = getpid();
> +
> +       /* check whether it can load program */
> +       err = bpf_syscall_macro__load(skel);
> +       if (!ASSERT_OK(err, "bpf_syscall_macro__load"))
> +               goto cleanup;
> +
> +       /* check whether it can attach kprobe */
> +       err = bpf_syscall_macro__attach(skel);
> +       if (!ASSERT_OK(err, "bpf_syscall_macro__attach"))
> +               goto cleanup;
> +
> +       /* check whether args of syscall are copied correctly */
> +       prctl(exp_arg1, exp_arg2, exp_arg3, exp_arg4, exp_arg5);
> +       ASSERT_EQ(skel->bss->arg1, exp_arg1, "syscall_arg1");
> +       ASSERT_EQ(skel->bss->arg2, exp_arg2, "syscall_arg2");
> +       ASSERT_EQ(skel->bss->arg3, exp_arg3, "syscall_arg3");
> +       /* it cannot copy arg4 when uses PT_REGS_PARM4 on x86_64 */
> +#ifdef __x86_64__
> +       ASSERT_NEQ(skel->bss->arg4_cx, exp_arg4, "syscall_arg4_from_cx");
> +#endif

else ASSERT_EQ(arg4_cx and exp_arg4) ?

> +       ASSERT_EQ(skel->bss->arg4, exp_arg4, "syscall_arg4");
> +       ASSERT_EQ(skel->bss->arg5, exp_arg5, "syscall_arg5");
> +
> +cleanup:
> +       bpf_syscall_macro__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
> new file mode 100644
> index 000000000000..5a7063de27c3
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright 2022 Sony Group Corporation */
> +#include <linux/bpf.h>
> +#include <linux/ptrace.h>
> +#include <sys/types.h>
> +#include <unistd.h>

Use #include <vmlinux.h> instead, please

> +
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include "bpf_misc.h"
> +
> +int arg1 = 0;
> +unsigned long arg2 = 0;
> +unsigned long arg3 = 0;
> +unsigned long arg4_cx = 0;
> +unsigned long arg4 = 0;
> +unsigned long arg5 = 0;
> +
> +const volatile pid_t filter_pid = 0;
> +
> +SEC("kprobe/" SYS_PREFIX "sys_prctl")
> +int BPF_KPROBE(handle_sys_prctl)
> +{
> +       struct pt_regs *real_regs;
> +       int orig_arg1;
> +       unsigned long orig_arg2, orig_arg3, orig_arg4_cx, orig_arg4, orig_arg5;
> +       pid_t pid = bpf_get_current_pid_tgid() >> 32;
> +
> +       if (pid != filter_pid)
> +               return 0;
> +
> +       real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);
> +       bpf_probe_read_kernel(&orig_arg1, sizeof(orig_arg1), &PT_REGS_PARM1_SYSCALL(real_regs));

orig_arg1 = PT_REGS_PARM1_CORE_SYSCALL(real_regs);

and same for others (the whole point of _CORE_SYSCALL macros!)


> +       bpf_probe_read_kernel(&orig_arg2, sizeof(orig_arg2), &PT_REGS_PARM2_SYSCALL(real_regs));
> +       bpf_probe_read_kernel(&orig_arg3, sizeof(orig_arg3), &PT_REGS_PARM3_SYSCALL(real_regs));
> +       bpf_probe_read_kernel(&orig_arg4_cx, sizeof(orig_arg4_cx), &PT_REGS_PARM4(real_regs));
> +       bpf_probe_read_kernel(&orig_arg4, sizeof(orig_arg4), &PT_REGS_PARM4_SYSCALL(real_regs));
> +       bpf_probe_read_kernel(&orig_arg5, sizeof(orig_arg5), &PT_REGS_PARM5_SYSCALL(real_regs));
> +
> +       /* copy all actual args and the wrong arg4 on x86_64 */
> +       arg1 = orig_arg1;
> +       arg2 = orig_arg2;
> +       arg3 = orig_arg3;
> +       arg4_cx = orig_arg4_cx;
> +       arg4 = orig_arg4;
> +       arg5 = orig_arg5;
> +
> +       return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.32.0
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c b/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
new file mode 100644
index 000000000000..2f725393195b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c
@@ -0,0 +1,49 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2022 Sony Group Corporation */
+#include <sys/prctl.h>
+#include <test_progs.h>
+#include "bpf_syscall_macro.skel.h"
+
+//void serial_bpf_syscall_macro(void)
+void test_bpf_syscall_macro(void)
+{
+	struct bpf_syscall_macro *skel = NULL;
+	int err;
+	int exp_arg1 = 1001;
+	unsigned long exp_arg2 = 12;
+	unsigned long exp_arg3 = 13;
+	unsigned long exp_arg4 = 14;
+	unsigned long exp_arg5 = 15;
+
+	/* check whether it can open program */
+	skel = bpf_syscall_macro__open();
+	if (!ASSERT_OK_PTR(skel, "bpf_syscall_macro__open"))
+		return;
+
+	skel->rodata->filter_pid = getpid();
+
+	/* check whether it can load program */
+	err = bpf_syscall_macro__load(skel);
+	if (!ASSERT_OK(err, "bpf_syscall_macro__load"))
+		goto cleanup;
+
+	/* check whether it can attach kprobe */
+	err = bpf_syscall_macro__attach(skel);
+	if (!ASSERT_OK(err, "bpf_syscall_macro__attach"))
+		goto cleanup;
+
+	/* check whether args of syscall are copied correctly */
+	prctl(exp_arg1, exp_arg2, exp_arg3, exp_arg4, exp_arg5);
+	ASSERT_EQ(skel->bss->arg1, exp_arg1, "syscall_arg1");
+	ASSERT_EQ(skel->bss->arg2, exp_arg2, "syscall_arg2");
+	ASSERT_EQ(skel->bss->arg3, exp_arg3, "syscall_arg3");
+	/* it cannot copy arg4 when uses PT_REGS_PARM4 on x86_64 */
+#ifdef __x86_64__
+	ASSERT_NEQ(skel->bss->arg4_cx, exp_arg4, "syscall_arg4_from_cx");
+#endif
+	ASSERT_EQ(skel->bss->arg4, exp_arg4, "syscall_arg4");
+	ASSERT_EQ(skel->bss->arg5, exp_arg5, "syscall_arg5");
+
+cleanup:
+	bpf_syscall_macro__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
new file mode 100644
index 000000000000..5a7063de27c3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_syscall_macro.c
@@ -0,0 +1,51 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2022 Sony Group Corporation */
+#include <linux/bpf.h>
+#include <linux/ptrace.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+
+int arg1 = 0;
+unsigned long arg2 = 0;
+unsigned long arg3 = 0;
+unsigned long arg4_cx = 0;
+unsigned long arg4 = 0;
+unsigned long arg5 = 0;
+
+const volatile pid_t filter_pid = 0;
+
+SEC("kprobe/" SYS_PREFIX "sys_prctl")
+int BPF_KPROBE(handle_sys_prctl)
+{
+	struct pt_regs *real_regs;
+	int orig_arg1;
+	unsigned long orig_arg2, orig_arg3, orig_arg4_cx, orig_arg4, orig_arg5;
+	pid_t pid = bpf_get_current_pid_tgid() >> 32;
+
+	if (pid != filter_pid)
+		return 0;
+
+	real_regs = (struct pt_regs *)PT_REGS_PARM1(ctx);
+	bpf_probe_read_kernel(&orig_arg1, sizeof(orig_arg1), &PT_REGS_PARM1_SYSCALL(real_regs));
+	bpf_probe_read_kernel(&orig_arg2, sizeof(orig_arg2), &PT_REGS_PARM2_SYSCALL(real_regs));
+	bpf_probe_read_kernel(&orig_arg3, sizeof(orig_arg3), &PT_REGS_PARM3_SYSCALL(real_regs));
+	bpf_probe_read_kernel(&orig_arg4_cx, sizeof(orig_arg4_cx), &PT_REGS_PARM4(real_regs));
+	bpf_probe_read_kernel(&orig_arg4, sizeof(orig_arg4), &PT_REGS_PARM4_SYSCALL(real_regs));
+	bpf_probe_read_kernel(&orig_arg5, sizeof(orig_arg5), &PT_REGS_PARM5_SYSCALL(real_regs));
+
+	/* copy all actual args and the wrong arg4 on x86_64 */
+	arg1 = orig_arg1;
+	arg2 = orig_arg2;
+	arg3 = orig_arg3;
+	arg4_cx = orig_arg4_cx;
+	arg4 = orig_arg4;
+	arg5 = orig_arg5;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";