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bpf/selftests: Test PTR_TO_RDONLY_MEM

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

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-10-haoluo@google.com
This commit is contained in:
Hao Luo 2021-12-16 16:31:52 -08:00 committed by Alexei Starovoitov
parent 216e3cd2f2
commit 9497c458c1
2 changed files with 43 additions and 0 deletions
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14
tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
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@ -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 @@ cleanup:
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();
}

29
tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c Normal file
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@ -0,0 +1,29 @@
// 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";