[PATCH bpf-next v2 3/3] bpf/selftests: Test PTR_TO_RDONLY_MEM
From: Hao Luo <hidden>
Date: 2021-10-25 23:13:09
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds
This test verifies that a ksym of non-struct can not be directly updated. Signed-off-by: Hao Luo <redacted> --- Changes since v1: - Replaced CHECK() with ASSERT_ERR_PTR() - Commented in the test for the reason of verification failure. .../selftests/bpf/prog_tests/ksyms_btf.c | 14 +++++++++ .../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
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index cf3acfa5a91d..69455fe90ac3 100644
--- 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 @@ static void test_weak_syms(void) 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(); }
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
new file mode 100644
index 000000000000..2180c41cd890
--- /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";
--
2.33.0.1079.g6e70778dc9-goog