[PATCH 5.8 172/633] selftests/bpf: Fix test_vmlinux test to use bpf_probe_read_user()

From: Greg Kroah-Hartman
Date: Tue Oct 27 2020 - 13:06:38 EST


From: Andrii Nakryiko <andriin@xxxxxx>

[ Upstream commit 02f47faa25db134f6043fb6b12a68b5d4c980bb6 ]

The test is reading UAPI kernel structure from user-space. So it doesn't need
CO-RE relocations and has to use bpf_probe_read_user().

Fixes: acbd06206bbb ("selftests/bpf: Add vmlinux.h selftest exercising tracing of syscalls")
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-6-andriin@xxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/testing/selftests/bpf/progs/test_vmlinux.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_vmlinux.c b/tools/testing/selftests/bpf/progs/test_vmlinux.c
index 5611b564d3b1c..f54b2293c490f 100644
--- a/tools/testing/selftests/bpf/progs/test_vmlinux.c
+++ b/tools/testing/selftests/bpf/progs/test_vmlinux.c
@@ -19,12 +19,14 @@ SEC("tp/syscalls/sys_enter_nanosleep")
int handle__tp(struct trace_event_raw_sys_enter *args)
{
struct __kernel_timespec *ts;
+ long tv_nsec;

if (args->id != __NR_nanosleep)
return 0;

ts = (void *)args->args[0];
- if (BPF_CORE_READ(ts, tv_nsec) != MY_TV_NSEC)
+ if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
+ tv_nsec != MY_TV_NSEC)
return 0;

tp_called = true;
@@ -35,12 +37,14 @@ SEC("raw_tp/sys_enter")
int BPF_PROG(handle__raw_tp, struct pt_regs *regs, long id)
{
struct __kernel_timespec *ts;
+ long tv_nsec;

if (id != __NR_nanosleep)
return 0;

ts = (void *)PT_REGS_PARM1_CORE(regs);
- if (BPF_CORE_READ(ts, tv_nsec) != MY_TV_NSEC)
+ if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
+ tv_nsec != MY_TV_NSEC)
return 0;

raw_tp_called = true;
@@ -51,12 +55,14 @@ SEC("tp_btf/sys_enter")
int BPF_PROG(handle__tp_btf, struct pt_regs *regs, long id)
{
struct __kernel_timespec *ts;
+ long tv_nsec;

if (id != __NR_nanosleep)
return 0;

ts = (void *)PT_REGS_PARM1_CORE(regs);
- if (BPF_CORE_READ(ts, tv_nsec) != MY_TV_NSEC)
+ if (bpf_probe_read_user(&tv_nsec, sizeof(ts->tv_nsec), &ts->tv_nsec) ||
+ tv_nsec != MY_TV_NSEC)
return 0;

tp_btf_called = true;
--
2.25.1