Commit 9497c458 authored by Hao Luo's avatar Hao Luo Committed by Alexei Starovoitov
Browse files

bpf/selftests: Test PTR_TO_RDONLY_MEM 



This test verifies that a ksym of non-struct can not be directly
updated.

Signed-off-by: default avatarHao Luo <haoluo@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-10-haoluo@google.com
parent 216e3cd2

tools/testing/selftests/bpf/prog_tests/ksyms_btf.c

+14 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include "test_ksyms_btf_null_check.skel.h"

#include "test_ksyms_weak.skel.h"

#include "test_ksyms_weak.lskel.h"

#include "test_ksyms_btf_write_check.skel.h"



static int duration;
@@ -137,6 +138,16 @@ static void test_weak_syms_lskel(void) 
	test_ksyms_weak_lskel__destroy(skel);

}



static void test_write_check(void)

{

	struct test_ksyms_btf_write_check *skel;



	skel = test_ksyms_btf_write_check__open_and_load();

	ASSERT_ERR_PTR(skel, "unexpected load of a prog writing to ksym memory\n");



	test_ksyms_btf_write_check__destroy(skel);

}



void test_ksyms_btf(void)

{

	int percpu_datasec;
@@ -167,4 +178,7 @@ void test_ksyms_btf(void) 


	if (test__start_subtest("weak_ksyms_lskel"))

		test_weak_syms_lskel();



	if (test__start_subtest("write_check"))

		test_write_check();

}

tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c

0 → 100644
+29 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Google */



#include "vmlinux.h"



#include <bpf/bpf_helpers.h>



extern const int bpf_prog_active __ksym; /* int type global var. */



SEC("raw_tp/sys_enter")

int handler(const void *ctx)

{

	int *active;

	__u32 cpu;



	cpu = bpf_get_smp_processor_id();

	active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);

	if (active) {

		/* Kernel memory obtained from bpf_{per,this}_cpu_ptr

		 * is read-only, should _not_ pass verification.

		 */

		/* WRITE_ONCE */

		*(volatile int *)active = -1;

	}



	return 0;

}



char _license[] SEC("license") = "GPL";