From: Hao Luo haoluo@google.com
commit 9497c458c10b049438ef6e6ddda898edbc3ec6a8 upstream.
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 Cc: stable@vger.kernel.org # 5.15.x Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/bpf/prog_tests/ksyms_btf.c | 14 ++++ tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c | 29 ++++++++++ 2 files changed, 43 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c @@ -7,6 +7,7 @@ #include "test_ksyms_btf.skel.h" #include "test_ksyms_btf_null_check.skel.h" #include "test_ksyms_weak.skel.h" +#include "test_ksyms_btf_write_check.skel.h"
static int duration;
@@ -109,6 +110,16 @@ cleanup: test_ksyms_weak__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; @@ -136,4 +147,7 @@ void test_ksyms_btf(void)
if (test__start_subtest("weak_ksyms")) test_weak_syms(); + + if (test__start_subtest("write_check")) + test_write_check(); } --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c @@ -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";